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cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet edit-page menu__item--page-actions-edit"> Edit </a> </li> </ul> </nav>  <div id="mw-content-subtitle"></div> </div> <div id="bodyContent" class="content"> <div id="mw-content-text" class="mw-body-content"><script>function mfTempOpenSection(id){var block=document.getElementById("mf-section-"+id);block.className+=" open-block";block.previousSibling.className+=" open-block";}</script><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><section class="mf-section-0" id="mf-section-0"> The human sex ratio is the <a href="/wiki/Ratio" title="Ratio">ratio</a> of <a href="/wiki/Male" title="Male">males</a> to <a href="/wiki/Female" title="Female">females</a> in a <a href="/wiki/Population" title="Population">population</a> in the context of <a href="/wiki/Anthropology" title="Anthropology">anthropology</a> and <a href="/wiki/Demography" title="Demography">demography</a>. In humans, the natural <a href="/wiki/Sex_ratio" title="Sex ratio">sex ratio</a> at birth is slightly biased towards the male sex. It is estimated to be about 1.10<a href="#cite_note-who.int-1">[1]</a> or 1.06<a href="#cite_note-2">[2]</a> or within a narrow range from 1.03 to 1.06<a href="#cite_note-naturalratio-3">[3]</a> males per female. The sex ratio for the entire <a href="/wiki/World_population" title="World population">world population</a> is approximately 101 males to 100 females (2020 est.).<a href="#cite_note-CIA_Fact_Book-4">[4]</a> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Sex_ratio_total_population_per_country_2020_(age_0-14).svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Sex_ratio_total_population_per_country_2020_%28age_0-14%29.svg/300px-Sex_ratio_total_population_per_country_2020_%28age_0-14%29.svg.png" decoding="async" width="300" height="134" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Sex_ratio_total_population_per_country_2020_%28age_0-14%29.svg/450px-Sex_ratio_total_population_per_country_2020_%28age_0-14%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Sex_ratio_total_population_per_country_2020_%28age_0-14%29.svg/600px-Sex_ratio_total_population_per_country_2020_%28age_0-14%29.svg.png 2x" data-file-width="2911" data-file-height="1297"></a><figcaption>Sex ratio by country for the population below age 15. Blue represents more boys, red more girls than the world average of 1.07 males/female.</figcaption></figure> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Sex_ratio_total_population_per_country_2020.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Sex_ratio_total_population_per_country_2020.svg/300px-Sex_ratio_total_population_per_country_2020.svg.png" decoding="async" width="300" height="134" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Sex_ratio_total_population_per_country_2020.svg/450px-Sex_ratio_total_population_per_country_2020.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/70/Sex_ratio_total_population_per_country_2020.svg/600px-Sex_ratio_total_population_per_country_2020.svg.png 2x" data-file-width="2911" data-file-height="1297"></a><figcaption>Sex ratio by country for total population. Blue represents more men and boys, red more women and girls than the world average of 1.01 males/female.</figcaption></figure> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Sex_ratio_total_population_per_country_2020_(ages_over_65).svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/21/Sex_ratio_total_population_per_country_2020_%28ages_over_65%29.svg/300px-Sex_ratio_total_population_per_country_2020_%28ages_over_65%29.svg.png" decoding="async" width="300" height="134" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/21/Sex_ratio_total_population_per_country_2020_%28ages_over_65%29.svg/450px-Sex_ratio_total_population_per_country_2020_%28ages_over_65%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/21/Sex_ratio_total_population_per_country_2020_%28ages_over_65%29.svg/600px-Sex_ratio_total_population_per_country_2020_%28ages_over_65%29.svg.png 2x" data-file-width="2911" data-file-height="1297"></a><figcaption>Sex ratio by country for the over-65 population. Blue represents more men, red more women than the world average of 0.81 males/female.</figcaption></figure> The sex ratios at birth and of the total population are affected by various factors including natural factors, exposure to pesticides and environmental contaminants,<a href="#cite_note-5">[5]</a><a href="#cite_note-6">[6]</a> war casualties, <a href="/wiki/Returning_soldier_effect" title="Returning soldier effect">effects of war on men</a>, <a href="/wiki/Sex-selective_abortions" class="mw-redirect" title="Sex-selective abortions">sex-selective abortions</a>, infanticides,<a href="#cite_note-7">[7]</a> aging, <a href="/wiki/Gendercide" title="Gendercide">gendercide</a>, problems with <a href="/wiki/Birth_registration" class="mw-redirect" title="Birth registration">birth registration</a> and <a href="/wiki/Life_expectancy#Sex_differences" title="Life expectancy">sex differences in life expectancy</a>.<a href="#cite_note-who.int-1">[1]</a> Human sex ratios, either at birth or in the population as a whole, can be reported in any of four ways: the ratio of males to females, the ratio of females to males, the proportion of males, or the proportion of females. If there are 108,000 males and 100,000 females the ratio of males to females is 1.08 and the proportion of males is 51.9%. Scientific literature often uses the proportion of males. This article uses the ratio of males to females, unless specified otherwise. <div id="toc" class="toc" role="navigation" aria-labelledby="mw-toc-heading"><input type="checkbox" role="button" id="toctogglecheckbox" class="toctogglecheckbox" style="display:none"><div class="toctitle" lang="en" dir="ltr"><h2 id="mw-toc-heading">Contents</h2><label class="toctogglelabel" for="toctogglecheckbox"></label></div> <ul> <li class="toclevel-1 tocsection-1"><a href="#Natural_ratio_at_birth">1 Natural ratio at birth</a> <ul> <li class="toclevel-2 tocsection-2"><a href="#History">1.1 History</a></li> </ul> </li> <li class="toclevel-1 tocsection-3"><a href="#Factors_affecting_sex_ratio_in_humans">2 Factors affecting sex ratio in humans</a> <ul> <li class="toclevel-2 tocsection-4"><a href="#Fisher's_principle">2.1 Fisher's principle</a></li> <li class="toclevel-2 tocsection-5"><a href="#Natural_factors">2.2 Natural factors</a> <ul> <li class="toclevel-3 tocsection-6"><a href="#Multiple_birth">2.2.1 Multiple birth</a></li> <li class="toclevel-3 tocsection-7"><a href="#Length_of_gestation">2.2.2 Length of gestation</a></li> </ul> </li> <li class="toclevel-2 tocsection-8"><a href="#Environmental_factors">2.3 Environmental factors</a> <ul> <li class="toclevel-3 tocsection-9"><a href="#Effects_of_climate_change">2.3.1 Effects of climate change</a></li> <li class="toclevel-3 tocsection-10"><a href="#Effects_of_gestation_environment">2.3.2 Effects of gestation environment</a></li> <li class="toclevel-3 tocsection-11"><a href="#Effects_of_chemical_pollution">2.3.3 Effects of chemical pollution</a></li> </ul> </li> <li class="toclevel-2 tocsection-12"><a href="#Social_factors">2.4 Social factors</a> <ul> <li class="toclevel-3 tocsection-13"><a href="#Population_composition">2.4.1 Population composition</a></li> <li class="toclevel-3 tocsection-14"><a href="#Effects_of_war">2.4.2 Effects of war</a></li> <li class="toclevel-3 tocsection-15"><a href="#Early_marriage_and_parents'_age">2.4.3 Early marriage and parents' age</a></li> <li class="toclevel-3 tocsection-16"><a href="#Partnership_status">2.4.4 Partnership status</a></li> </ul> </li> <li class="toclevel-2 tocsection-17"><a href="#Economic_factors">2.5 Economic factors</a></li> <li class="toclevel-2 tocsection-18"><a href="#Sex-selective_abortion_and_infanticide">2.6 Sex-selective abortion and infanticide</a></li> </ul> </li> <li class="toclevel-1 tocsection-19"><a href="#Data_sources_and_data_quality_issues">3 Data sources and data quality issues</a></li> <li class="toclevel-1 tocsection-20"><a href="#Countries_with_imbalances_in_sex_ratio">4 Countries with imbalances in sex ratio</a></li> <li class="toclevel-1 tocsection-21"><a href="#Consequences_of_different_sex_ratios">5 Consequences of different sex ratios</a></li> <li class="toclevel-1 tocsection-22"><a href="#See_also">6 See also</a></li> <li class="toclevel-1 tocsection-23"><a href="#References">7 References</a></li> </ul> </div> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(1)"><h2 id="Natural_ratio_at_birth">Natural ratio at birth</h2> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=1" title="Edit section: Natural ratio at birth" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div><section class="mf-section-1 collapsible-block" id="mf-section-1"> <figure typeof="mw:File/Thumb"><a href="/wiki/File:2012_Birth_Sex_Ratio_World_Map.jpg" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/ac/2012_Birth_Sex_Ratio_World_Map.jpg/300px-2012_Birth_Sex_Ratio_World_Map.jpg" decoding="async" width="300" height="137" class="mw-file-element" data-file-width="1800" data-file-height="820"></noscript><span class="lazy-image-placeholder" style="width: 300px;height: 137px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/a/ac/2012_Birth_Sex_Ratio_World_Map.jpg/300px-2012_Birth_Sex_Ratio_World_Map.jpg" data-width="300" data-height="137" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/ac/2012_Birth_Sex_Ratio_World_Map.jpg/450px-2012_Birth_Sex_Ratio_World_Map.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/ac/2012_Birth_Sex_Ratio_World_Map.jpg/600px-2012_Birth_Sex_Ratio_World_Map.jpg 2x" data-class="mw-file-element"> </a><figcaption>World map of birth sex ratios, 2012. Gray = no data</figcaption></figure> In a study around 2002, the natural sex ratio at birth was estimated to be within a narrow range of 1.07 to 1.03 males/female.<a href="#cite_note-naturalratio-3">[3]</a><a href="#cite_note-8">[8]</a> Some scholars suggest that countries considered to have significant practices of prenatal sex-selection are those with birth sex ratios of 1.08 and above (selection against females) and 1.02 and below (selection against males). This assumption has been questioned by some scholars.<a href="#cite_note-James-JournalofEndocrinology-9">[9]</a> Infant mortality is significantly higher in boys than girls in most parts of the world. Often this is explained as due to biological and genetic sex differences, with boys more biologically vulnerable to premature death and disease.<a href="#cite_note-10">[10]</a><a href="#cite_note-11">[11]</a> Recent studies have found that numerous preconception or prenatal environmental factors affect the probabilities of a baby being conceived male or female. It has been proposed that these environmental factors also explain sex differences in mortality.<a href="#cite_note-12">[12]</a> In most populations, adult males tend to have higher death rates than adult females of the same age (even after allowing for causes specific to females such as death in childbirth), due to both natural causes such as heart attacks and strokes, which account for by far the majority of deaths, and also violent causes, such as homicide and warfare. Thus females have a higher <a href="/wiki/Life_expectancy" title="Life expectancy">life expectancy</a>. For example, in the United States, as of 2006, an adult non-elderly male was 3 to 6 times more likely to become a victim of a homicide and 2.5 to 3.5 times more likely to die in an accident than a female of the same age.<a href="#cite_note-13">[13]</a> In the United States, the sex ratios at birth over the period 1970–2002 were 1.05 for the white non-Hispanic population, 1.04 for Mexican Americans, 1.03 for African Americans and Indians, and 1.07 for mothers of Chinese or Filipino ethnicity.<a href="#cite_note-14">[14]</a> Among Western European countries around 2001, the ratios ranged from 1.04 in Belgium to 1.07 in Switzerland,<a href="#cite_note-15">[15]</a> Italy,<a href="#cite_note-16">[16]</a> Ireland<a href="#cite_note-17">[17]</a> and Portugal. In the aggregated results of 56 demographic and health surveys<a href="#cite_note-18">[18]</a> in African countries, the ratio is 1.03, not with considerable country-to-country variation.<a href="#cite_note-19">[19]</a> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:PRC_family_planning_don%27t_abandon_girls.jpg" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/PRC_family_planning_don%27t_abandon_girls.jpg/220px-PRC_family_planning_don%27t_abandon_girls.jpg" decoding="async" width="220" height="156" class="mw-file-element" data-file-width="819" data-file-height="580"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 156px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/PRC_family_planning_don%27t_abandon_girls.jpg/220px-PRC_family_planning_don%27t_abandon_girls.jpg" data-width="220" data-height="156" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/PRC_family_planning_don%27t_abandon_girls.jpg/330px-PRC_family_planning_don%27t_abandon_girls.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4e/PRC_family_planning_don%27t_abandon_girls.jpg/440px-PRC_family_planning_don%27t_abandon_girls.jpg 2x" data-class="mw-file-element"> </a><figcaption>A roadside sign in rural <a href="/wiki/Sichuan" title="Sichuan">Sichuan</a>: "It is forbidden to discriminate against, abuse or abandon baby girls."</figcaption></figure> There is controversy about whether sex ratios outside the 1.03–1.07 range are due to sex selection, as suggested by some scholars, or due to natural causes. Some scholars argue that strong socioeconomic factors such as the <a href="/wiki/Dowry_system_in_India" title="Dowry system in India">dowry system in India</a> and the <a href="/wiki/One_child_policy" class="mw-redirect" title="One child policy">one child policy</a> of China are responsible for prenatal sex selection. In a widely cited article,<a href="#cite_note-Sen1990-20">[20]</a> <a href="/wiki/Amartya_Sen" title="Amartya Sen">Amartya Sen</a> supported such views. Other researchers argue that an unbalanced sex ratio should not be automatically held as evidence of prenatal sex selection; Michel Garenne reports that many African nations have, over decades, had birth sex ratios below 1.00: that is, more girls are born than boys.<a href="#cite_note-21">[21]</a> Angola, Botswana and Namibia have reported birth sex ratios between 0.94 and 0.99, which is quite different from the presumed "normal" sex ratio, meaning that significantly more girls have been born in such countries.<a href="#cite_note-22">[22]</a> In an extensive study, carried out around 2005, of sex ratio at birth in the United States from 1940 over 62 years, statistical evidence suggested the following:<a href="#cite_note-NCHS-23">[23]</a> <ul><li>For mothers having their first baby, the total sex ratio at birth was 1.06 overall, with some years at 1.07.</li> <li>For mothers having babies after the first, this ratio consistently decreased with each additional baby from 1.07 towards 1.03.</li> <li>The age of the mother affected the ratio: <ul><li>the overall ratio was 1.05 for mothers aged 25 to 35 at the time of birth</li> <li>mothers who were below the age of 15 or above 40 had babies with a sex ratio ranging between 0.94 and 1.11,[<a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify">clarification needed</a>] and a total sex ratio of 1.05</li></ul></li></ul> <div class="mw-heading mw-heading3"><h3 id="History">History</h3> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=2" title="Edit section: History" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> The human sex ratio at birth has been an object of study since early in the <a href="/wiki/History_of_statistics" title="History of statistics">history of statistics</a>, as it is easily recorded and a large number for sufficiently large populations.<a href="#cite_note-24">[24]</a> An early researcher was <a href="/wiki/John_Arbuthnot" title="John Arbuthnot">John Arbuthnot</a> (1710),<a href="#cite_note-25">[25]</a><a href="#cite_note-Conover1999-26">[26]</a><a href="#cite_note-Sprent1989-27">[27]</a><a href="#cite_note-Stigler1986-28">[28]</a> who in modern terms, performed <a href="/wiki/Statistical_hypothesis_testing" class="mw-redirect" title="Statistical hypothesis testing">statistical hypothesis testing</a>, computing the <a href="/wiki/P-value" title="P-value">p-value</a> (via a <a href="/wiki/Sign_test" title="Sign test">sign test</a>), interpreted it as <a href="/wiki/Statistical_significance" title="Statistical significance">statistical significance</a>, and rejected the <a href="/wiki/Null_hypothesis" title="Null hypothesis">null hypothesis</a>.<a href="#cite_note-Bellhouse2001-29">[29]</a> Human sex at birth was also analyzed and used as an example by <a href="/wiki/Jacob_Bernoulli" title="Jacob Bernoulli">Jacob Bernoulli</a> in <a href="/wiki/Ars_Conjectandi" title="Ars Conjectandi">Ars Conjectandi</a> (1713), in which an unequal sex ratio is a natural example of a <a href="/wiki/Bernoulli_trial" title="Bernoulli trial">Bernoulli trial</a> with uneven odds. <a href="/wiki/Willem_%27s_Gravesande" title="Willem 's Gravesande">Willem 's Gravesande</a> (1774) also studied it.<a href="#cite_note-Stigler1986-28">[28]</a> <a href="/wiki/Pierre-Simon_Laplace" title="Pierre-Simon Laplace">Pierre-Simon Laplace</a> (1778) used human sex ratio as an example in his development of <a href="/wiki/Probability_theory" title="Probability theory">probability theory</a>. He considered the statistics of almost half a million births; the statistics showed an excess of boys compared to girls.<a href="#cite_note-Laplace_1778-30">[30]</a><a href="#cite_note-Laplace_1878-31">[31]</a> He concluded by calculation of a p-value that the excess was a real, but unexplained, effect.<a href="#cite_note-32">[32]</a> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(2)"><h2 id="Factors_affecting_sex_ratio_in_humans">Factors affecting sex ratio in humans</h2> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=3" title="Edit section: Factors affecting sex ratio in humans" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div><section class="mf-section-2 collapsible-block" id="mf-section-2"> <div class="mw-heading mw-heading3"><h3 id="Fisher's_principle">Fisher's principle</h3> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=4" title="Edit section: Fisher's principle" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> <a href="/wiki/Fisher%27s_principle" title="Fisher's principle">Fisher's principle</a> is an explanation of why the sex ratio of most species is approximately 1:1. Outlined by <a href="/wiki/Ronald_Fisher" title="Ronald Fisher">Ronald Fisher</a> in his 1930 book, it is an argument in terms of parental expenditure. Essentially he argues that the 1:1 ratio is the <a href="/wiki/Evolutionarily_stable_strategy" title="Evolutionarily stable strategy">evolutionarily stable strategy</a>.<a href="#cite_note-Fisher-33">[33]</a><a href="#cite_note-Hamilton-34">[34]</a> Many species deviate from an even sex ratio, either periodically or permanently. Examples include <a href="/wiki/Parthenogenic" class="mw-redirect" title="Parthenogenic">parthenogenic</a> species, periodically mating organisms such as <a href="/wiki/Aphid" title="Aphid">aphids</a>, some <a href="/wiki/Eusociality" title="Eusociality">eusocial</a> <a href="/wiki/Wasp" title="Wasp">wasps</a>, <a href="/wiki/Bee" title="Bee">bees</a>, <a href="/wiki/Ant" title="Ant">ants</a>, and <a href="/wiki/Termite" title="Termite">termites</a>.<a href="#cite_note-35">[35]</a> <div class="mw-heading mw-heading3"><h3 id="Natural_factors">Natural factors</h3> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=5" title="Edit section: Natural factors" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> The natural factors that affect the human sex ratio are an active area of scientific research. Over 1000 articles have been published in various journals. Two of the often cited reviews of scientific studies on human sex ratio are by W. H. James.<a href="#cite_note-36">[36]</a><a href="#cite_note-37">[37]</a> The scientific studies are based on extensive birth and death records in Africa, the Americas, Asia, Australia, and Europe. A few of these studies extend to over 100 years of yearly human sex ratio data for some countries. These studies suggest that the human sex ratio, both at birth and as a population matures, can vary significantly according to a large number of factors, such as paternal age, maternal age, <a href="/wiki/Multiple_birth" title="Multiple birth">multiple births</a>, <a href="/wiki/Birth_order" title="Birth order">birth order</a>, gestation weeks, race, parent's health history, and parent's psychological stress. Remarkably, the trends in human sex ratio are not consistent across countries at a given time, or over time for a given country. In economically developed countries, as well as developing countries, these scientific studies have found that the human sex ratio at birth has historically varied between 0.94 and 1.15 for natural reasons. In a scientific paper published in 2008,<a href="#cite_note-James-JournalofEndocrinology-9">[9]</a> James states that conventional assumptions have been: <ul><li>there are equal numbers of X and Y chromosomes in mammalian sperm</li> <li>X and Y stand equal chance of achieving conception</li> <li>therefore equal numbers of male and female zygotes are formed</li> <li>therefore any variation of sex ratio at birth is due to sex selection between conception and birth.</li></ul> James cautions that available scientific evidence stands against the above assumptions and conclusions. He reports that there is an excess of males at birth in almost all human populations, and the natural sex ratio at birth is usually between 1.02 and 1.08. However, the ratio may deviate significantly from this range for natural reasons. An analysis study from 2015 showed that human sex ratio at conception is roughly 50%, but rises due to total mortality surplus of female embryos.<a href="#cite_note-concepbirth-38">[38]</a> A dataset of 139,704 embryos derived from <a href="/wiki/Assisted_reproductive_technology" title="Assisted reproductive technology">assisted reproductive technology</a> showed a male sex ratio of 50.2%.<a href="#cite_note-concepbirth-38">[38]</a> A dataset of 4,999 embryos from <a href="/wiki/Induced_abortion" class="mw-redirect" title="Induced abortion">induced abortions</a> showed a rate of 51.1% for the first <a href="/wiki/Trimester_(pregnancy)" class="mw-redirect" title="Trimester (pregnancy)">trimester</a> and 55.9% for the last two trimesters.<a href="#cite_note-concepbirth-38">[38]</a> <div class="mw-heading mw-heading4"><h4 id="Multiple_birth">Multiple birth</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=6" title="Edit section: Multiple birth" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> A 1999 scientific paper published by Jacobsen reported the sex ratio for 815,891 children born in Denmark between 1980 and 1993.<a href="#cite_note-39">[39]</a> They studied the birth records to identify the effects of <a href="/wiki/Multiple_birth" title="Multiple birth">multiple birth</a>, birth order, age of parents and the sexes of preceding siblings on the proportion of males using contingency tables, <a href="/wiki/Chi-squared_test" title="Chi-squared test">chi-squared tests</a> and regression analysis. The secondary sex ratio decreased with increasing number of children per plural birth and with paternal age, whereas no significant independent effect was observed for maternal age, birth order, or other natural factors. <div class="mw-heading mw-heading4"><h4 id="Length_of_gestation">Length of gestation</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=7" title="Edit section: Length of gestation" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> A 2009 research paper published by Branum et al. reports the sex ratio derived from data in United States birth records over a 25-year period (1981–2006).<a href="#cite_note-40">[40]</a> This paper reports that the sex ratio at birth for the white ethnic group in the United States was 1.04 when the gestational age was 33–36 weeks, but 1.15 for gestational ages of less than 28 weeks, 28–32 weeks, and 37 or more weeks. This study also found that the sex ratios at birth in the United States, between 1981 and 2006, were lower in both black and Hispanic ethnic groups when compared with non-Hispanic white ethnic group. A research group led by Ein-Mor reported that sex ratio does not seem to change significantly with either maternal or paternal age. Neither <a href="/wiki/Gravidity" class="mw-redirect" title="Gravidity">gravidity</a> nor <a href="/wiki/Parity_(medicine)" class="mw-redirect" title="Parity (medicine)">parity</a> seem to affect the male-to-female ratio.<a href="#cite_note-Ein-Mor-41">[41]</a> However, there is a significant association of sex ratio with the length of gestation.<a href="#cite_note-Ein-Mor-41">[41]</a> These Ein-mor conclusions have been disputed. For example, James suggested<a href="#cite_note-James-FertilSterilJournal-42">[42]</a> that Ein-Mor results are based on some demographic variables and a small data set, a broader study of variables and larger population set suggests human sex ratio shows substantial variation for various reasons and different trend effects of length of gestation than those reported by Ein-Mor. In another study, James has offered the hypothesis that human sex ratios, and mammalian sex ratios in general, are causally related to the hormone levels of both parents at the time of conception.<a href="#cite_note-James-JournalofEndocrinology-9">[9]</a> This hypothesis is yet to be tested and proven true or false over large population sets. <div class="mw-heading mw-heading3"><h3 id="Environmental_factors">Environmental factors</h3> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=8" title="Edit section: Environmental factors" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> <div class="mw-heading mw-heading4"><h4 id="Effects_of_climate_change">Effects of climate change</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=9" title="Edit section: Effects of climate change" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> Various scientists have examined the question whether human birth sex ratios have historically been affected by environmental stressors such as <a href="/wiki/Climate_change" title="Climate change">climate change</a> and global warming. Several studies show that high temperature raises proportion of male births, but the reasons for this are disputed.<a href="#cite_note-Helle_2009-43">[43]</a> Catalano et al. report that cold weather is an environmental stressor, and women subjected to colder weather abort frail male fetuses in greater proportion, thereby lowering birth sex ratios. Cold weather stressors also extend male longevity, thereby raising the human sex ratio at older ages.<a href="#cite_note-Catalano-44">[44]</a> The Catalano team found that a 1 °C increase in annual temperature predicts one more male than expected for every 1,000 females born in a year. Helle et al. studied 138 years of human birth sex ratio data, from 1865 to 2003. They find an increased excess of male births during periods of exogenous stress (World War II) and during warm years. In the warmest period over the 138 years, the birth sex ratio peaked at about 1.08 in Northern Europe.<a href="#cite_note-Helle_2009-43">[43]</a> The increase in the sex ratio for each 1 °C increase in temperature was approximately the same as the result found by the Catalano team.<a href="#cite_note-45">[45]</a> <div class="mw-heading mw-heading4"><h4 id="Effects_of_gestation_environment">Effects of gestation environment</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=10" title="Edit section: Effects of gestation environment" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> Causes of stress during gestation, such as maternal malnutrition,<a href="#cite_note-46">[46]</a> generally appear to increase fetal deaths, particularly among males,<a href="#cite_note-Catalano-44">[44]</a> resulting in a lower sex ratio at birth. A higher incidence of <a href="/wiki/Hepatitis_B" title="Hepatitis B">Hepatitis B</a> virus in a population is believed to increase the sex ratio, while some unexplained environmental health hazards are thought to have the opposite effect.<a href="#cite_note-47">[47]</a> The effects of gestational environment on human sex ratio are complicated and unclear, with numerous conflicting reports. For example, Oster et al. examined a data set of 67,000 births in China, 15 percent of whom were Hepatitis B carriers. They found no effect on birth sex ratio from Hepatitis B presence in either mothers or fathers.<a href="#cite_note-revision-48">[48]</a> <div class="mw-heading mw-heading4"><h4 id="Effects_of_chemical_pollution">Effects of chemical pollution</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=11" title="Edit section: Effects of chemical pollution" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:NonylphenolEstradiol.svg" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/NonylphenolEstradiol.svg/250px-NonylphenolEstradiol.svg.png" decoding="async" width="250" height="87" class="mw-file-element" data-file-width="344" data-file-height="120"></noscript><span class="lazy-image-placeholder" style="width: 250px;height: 87px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/NonylphenolEstradiol.svg/250px-NonylphenolEstradiol.svg.png" data-width="250" data-height="87" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/NonylphenolEstradiol.svg/375px-NonylphenolEstradiol.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b2/NonylphenolEstradiol.svg/500px-NonylphenolEstradiol.svg.png 2x" data-class="mw-file-element"> </a><figcaption>A comparison of the structures of the natural hormone <a href="/wiki/Estradiol" title="Estradiol">estradiol</a> (left) and one of the <a href="/wiki/Nonylphenol" title="Nonylphenol">nonyl-phenols</a> (right), an endocrine disruptor</figcaption></figure> A 2007 survey by the Arctic Monitoring and Assessment Program noted abnormally low sex ratios in Russian Arctic villages and <a href="/wiki/Inuit" title="Inuit">Inuit</a> villages in <a href="/wiki/Greenland" title="Greenland">Greenland</a> and Canada, and attributed this imbalance to high levels of <a href="/wiki/Endocrine_disruptor" title="Endocrine disruptor">endocrine disruptors</a> in the blood of inhabitants, including <a href="/wiki/Polychlorinated_biphenyl" title="Polychlorinated biphenyl">PCBs</a> and <a href="/wiki/DDT" title="DDT">DDT</a>. These chemicals are believed to have accumulated in the tissues of fish and animals that make up the bulk of these populations' diets.<a href="#cite_note-49">[49]</a> However, as noted in the <a href="#Social_factors">Social factors</a> section below, it is important to exclude alternative explanations, including social ones, when examining large human populations whose composition by ethnicity and race may be changing. A 2008 report provides further evidence of effects of <a href="/wiki/Xenoestrogens" class="mw-redirect" title="Xenoestrogens">feminizing chemicals</a> on male development in each class of <a href="/wiki/Vertebrate" title="Vertebrate">vertebrate</a> species as a worldwide phenomenon, possibly leading to a decline in the sex ratio in humans and a possible decline in <a href="/wiki/Sperm" title="Sperm">sperm</a> counts.<a href="#cite_note-indepen-50">[50]</a> Out of over 100,000 recently introduced chemicals, 99% are poorly regulated.<a href="#cite_note-indepen-50">[50]</a> Other factors that could possibly affect the sex ratio include: <ul><li>Social status of the mother, known to be a factor in influencing the sex ratio of certain animals such as swine,<a href="#cite_note-51">[51]</a> but apparently not in humans.<a href="#cite_note-52">[52]</a></li> <li>Whether the mother has a partner may have a small effect on sex ratio, with one study of 84,500 births finding 51.5% male births among women living with a partner, and 49.9% in women who were not.<a href="#cite_note-53">[53]</a></li> <li><a href="/wiki/Latitude" title="Latitude">Latitude</a>, with countries near the equator producing more females than near the poles.<a href="#cite_note-54">[54]</a></li></ul> Other scientific studies suggest that environmental effects on human sex ratio at birth are either limited or not properly understood. For example, a research paper published in 1999, by scientists from Finland's National Public Health Institute, reports the effect of environmental chemicals and changes in sex ratio over 250 years in Finland.<a href="#cite_note-55">[55]</a> This scientific team evaluated whether Finnish long-term data are compatible with the hypothesis that the decrease in the ratio of male to female births in industrial countries is caused by environmental factors. They analyzed the sex ratio of births from the files of Statistics Finland and all live births in Finland from 1751 to 1997. They found an increase in the proportion of males from 1751 to 1920; this was followed by a decrease and interrupted by peaks in births of males during and after World War I and World War II. None of the natural factors such as paternal age, maternal age, age difference of parents or birth order could explain the time trends. The scientists found that the peak sex ratio precedes the period of industrialization and the introduction of pesticides or hormonal drugs, rendering a causal association between environmental chemicals and human sex ratio at birth unlikely.[<a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify">clarification needed</a>] Moreover, these scientists claim that the trends they found in Finland are similar to those observed in other countries with higher levels of pollution and much greater pesticide use. Some studies have found that certain kinds of environmental <a href="/wiki/Pollution" title="Pollution">pollution</a>, specifically <a href="/wiki/Dioxin" title="Dioxin">dioxins</a>, are associated with a lower sex ratio.<a href="#cite_note-56">[56]</a><a href="#cite_note-57">[57]</a> <div class="mw-heading mw-heading3"><h3 id="Social_factors">Social factors</h3> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=12" title="Edit section: Social factors" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> <div class="mw-heading mw-heading4"><h4 id="Population_composition">Population composition</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=13" title="Edit section: Population composition" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> As an example of how the social composition of a human population may produce unusual changes in sex ratios, in a study in several counties of California where declining sex ratios had been observed, Smith and Von Behren observe "In the raw data, the male birth proportion is indeed declining. However, during this period, there were also shifts in demographics that influence the sex ratio. Controlling for birth order, parents' age, and race/ethnicity, different trends emerged. White births (which account for over 80%) continued to show a statistically significant decline, while other racial groups showed non-statistically significant declines (Japanese-American, Native American, other), with little or no change (Black American), or an increase (Chinese-American). Finally, when the white births were divided into Hispanic and non-Hispanic (possible since 1982), it was found that both white subgroups suggest an increase in male births." They concluded "that the decline in male births in California is largely attributable to changes in demographics."<a href="#cite_note-58">[58]</a> <div class="mw-heading mw-heading4"><h4 id="Effects_of_war">Effects of war</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=14" title="Edit section: Effects of war" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> Increased sex ratio during and after a war is called the <a href="/wiki/Returning_soldier_effect" title="Returning soldier effect">returning soldier effect</a>. There is still no clear explanation of its mechanics.<a href="#cite_note-59">[59]</a> <div class="mw-heading mw-heading4"><h4 id="Early_marriage_and_parents'_age">Early marriage and parents' age</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=15" title="Edit section: Early marriage and parents' age" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> Several studies have examined human birth sex ratio data to determine whether there is a natural relationship between the age of the mother or father and the birth sex ratio. For example, Ruder has studied 1.67 million births in 33 states in the United States to investigate the effect of parents' ages on birth sex ratios.<a href="#cite_note-60">[60]</a> Similarly, Jacobsen et al. have studied 820,000 births in Denmark with the same goal.<a href="#cite_note-61">[61]</a> These scientists find that maternal age has no statistically significant role on the human birth sex ratio. However, they report a significant effect of paternal age. Significantly more male babies were born per 1000 female babies to younger fathers than to older fathers. These studies suggest that social factors such as <a href="/wiki/Child_marriage" title="Child marriage">early marriage</a> and males siring their children at a young age may play a role in raising birth sex ratios in certain societies.<a href="#cite_note-62">[62]</a> <div class="mw-heading mw-heading4"><h4 id="Partnership_status">Partnership status</h4> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=16" title="Edit section: Partnership status" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> It has been shown on a sample of 86,436 human births from a US population-based survey that 51.4% boys were born among together living married parents, 52.2% among together living unmarried parents and only 49.9% boys among apart living parents.<a href="#cite_note-63">[63]</a> <div class="mw-heading mw-heading3"><h3 id="Economic_factors">Economic factors</h3> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=17" title="Edit section: Economic factors" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> Catalano has examined the hypothesis that population stress induced by a declining economy reduces the human sex ratio. He compared the sex ratio in East and West Germany for the years 1946 to 1999, with genetically similar populations. The population stressors theory predicts that the East German sex ratio should have been lower than expected in 1991, when East Germany's economy collapsed, than in previous years. The hypothesis further suggests that, over time, East German birth sex ratios should generally be lower than the observed sex ratios found in West Germany for the same years. According to Catalano's study, the birth sex ratio data from East Germany and West Germany over 45 years support the hypothesis. The sex ratio in East Germany was also at its lowest in 1991. According to Catalano's study, assuming women in East Germany did not opt to abort male fetuses more than female fetuses, the best hypothesis is that a collapsing economy lowers the human birth sex ratio, while a booming economy raises the birth sex ratio. Catalano notes that these trends may be related to the observed trend of an elevated occurrence of very <a href="/wiki/Low_birth-weight" class="mw-redirect" title="Low birth-weight">low birth-weight</a> babies from maternal stress, during certain macroeconomic circumstances.<a href="#cite_note-64">[64]</a> <div class="mw-heading mw-heading3"><h3 id="Sex-selective_abortion_and_infanticide">Sex-selective abortion and infanticide</h3> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=18" title="Edit section: Sex-selective abortion and infanticide" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Sex_determination_ban.JPG" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Sex_determination_ban.JPG/220px-Sex_determination_ban.JPG" decoding="async" width="220" height="165" class="mw-file-element" data-file-width="1024" data-file-height="768"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 165px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Sex_determination_ban.JPG/220px-Sex_determination_ban.JPG" data-width="220" data-height="165" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Sex_determination_ban.JPG/330px-Sex_determination_ban.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Sex_determination_ban.JPG/440px-Sex_determination_ban.JPG 2x" data-class="mw-file-element"> </a><figcaption>Sign in an Indian hospital stating that prenatal sex determination is not done there and is illegal</figcaption></figure> <a href="/wiki/Sex-selective_abortion" title="Sex-selective abortion">Sex-selective abortion</a> and <a href="/wiki/Infanticide" title="Infanticide">infanticide</a> are thought to significantly skew the naturally occurring ratio in some populations, such as China, where the introduction of ultrasound scans in the late 1980s has led to a birth sex ratio (males to females) of 1.181 (2010 official census data for China).<a href="#cite_note-65">[65]</a> The 2011 India census reports India's sex ratio in the 0–6 age bracket at 1.088.<a href="#cite_note-66">[66]</a> The 2011 birth sex ratios for China and India are significantly above the mean ratio recorded in the United States from 1940 through 2002 (1.051); however, their birth sex ratios are within the 0.98–1.14 range observed in the United States for major ethnic groups over the same time period.<a href="#cite_note-NCHS-23">[23]</a>: 10 Along with Asian countries, a number of European, Middle Eastern, and Latin American countries have recently reported high birth sex ratios in the 1.06 to 1.14 range. High birth sex ratios, according to some studies, can be caused in part by social factors. Another hypothesis has been inspired by the recent and persistent high birth sex ratios observed in <a href="/wiki/Georgia_(country)" title="Georgia (country)">Georgia</a> and <a href="/wiki/Armenia" title="Armenia">Armenia</a>—both predominantly Orthodox Christian societies—and <a href="/wiki/Azerbaijan" title="Azerbaijan">Azerbaijan</a>, a predominantly Muslim society. Since their independence from the Soviet Union, the birth sex ratio in these Caucasus countries has risen sharply, to between 1.11 and 1.20, among the world's highest. Mesle et al. consider the hypothesis that the high birth sex ratio may be because of the social trend of more than two children per family, and birth order possibly affects the sex ratio in this region of the world. They also consider the hypothesis that sons are preferred in these countries of the Caucasus, the spread of scans and there being a practice of sex-selective abortion; however, the scientists admit that they do not have definitive proof that sex-selective abortion is actually happening or that there are no natural reasons for the persistently high birth sex ratios.<a href="#cite_note-67">[67]</a> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(3)"><h2 id="Data_sources_and_data_quality_issues">Data sources and data quality issues</h2> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=19" title="Edit section: Data sources and data quality issues" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div><section class="mf-section-3 collapsible-block" id="mf-section-3"> For most of the 20th century in Russia (and the <a href="/wiki/Soviet_Union" title="Soviet Union">Soviet Union</a>), extremely premature newborns (less than 28 weeks gestational age, or less than 1000 grams in weight, or less than 35 centimeters in length) were not counted as a live birth until they had survived for seven days; if that infant died in those first 168 hours it, would not be counted as an infant death. This led to serious underreporting of the <a href="/wiki/Infant_mortality_rate" class="mw-redirect" title="Infant mortality rate">infant mortality rate</a> (by 22% to 25%) relative to standards recommended by the <a href="/wiki/World_Health_Organization" title="World Health Organization">World Health Organization</a>.<a href="#cite_note-68">[68]</a> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:China_1982_happy_family_with_one_child.jpg" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/China_1982_happy_family_with_one_child.jpg/220px-China_1982_happy_family_with_one_child.jpg" decoding="async" width="220" height="136" class="mw-file-element" data-file-width="1741" data-file-height="1077"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 136px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/China_1982_happy_family_with_one_child.jpg/220px-China_1982_happy_family_with_one_child.jpg" data-width="220" data-height="136" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/China_1982_happy_family_with_one_child.jpg/330px-China_1982_happy_family_with_one_child.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e4/China_1982_happy_family_with_one_child.jpg/440px-China_1982_happy_family_with_one_child.jpg 2x" data-class="mw-file-element"> </a><figcaption>A poster from 1982 showing a Chinese family with one child</figcaption></figure> Some researchers have, in part, attributed the high sex ratios reported in <a href="/wiki/Mainland_China" title="Mainland China">mainland China</a> in the last 25 years to the underreporting of the births of female children after the implementation of the <a href="/wiki/One-child_policy" title="One-child policy">one-child policy</a>, though alternative explanations are now generally more widely accepted, including, above all, the use of ultrasound technology and <a href="/wiki/Sex-selective_abortion" title="Sex-selective abortion">sex-selective abortion</a> of female fetuses and, probably to a more limited degree, neglect or in some cases <a href="/wiki/Infanticide" title="Infanticide">infanticide</a> of females. In the case of China, because of deficiencies in the <a href="/wiki/Vital_statistics_(government_records)" title="Vital statistics (government records)">vital statistics</a> registration system, studies of sex ratios at birth have relied either on special fertility surveys, whose accuracy depends on full reporting of births and survival of both male and female infants, or on the national <a href="/wiki/Population_census" class="mw-redirect" title="Population census">population census</a> from which both birth rates and death rates are calculated from the household's reporting of births and deaths in the 18 months preceding the census.<a href="#cite_note-69">[69]</a> To the extent that this underreporting of births or deaths is sex-selective, both fertility surveys and censuses may inaccurately reflect the actual sex ratios at birth.<a href="#cite_note-70">[70]</a> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(4)"><h2 id="Countries_with_imbalances_in_sex_ratio">Countries with imbalances in sex ratio</h2> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=20" title="Edit section: Countries with imbalances in sex ratio" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div><section class="mf-section-4 collapsible-block" id="mf-section-4"> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Pyramide_Bahrein.PNG" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Pyramide_Bahrein.PNG/220px-Pyramide_Bahrein.PNG" decoding="async" width="220" height="152" class="mw-file-element" data-file-width="902" data-file-height="625"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 152px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Pyramide_Bahrein.PNG/220px-Pyramide_Bahrein.PNG" data-width="220" data-height="152" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Pyramide_Bahrein.PNG/330px-Pyramide_Bahrein.PNG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/49/Pyramide_Bahrein.PNG/440px-Pyramide_Bahrein.PNG 2x" data-class="mw-file-element"> </a><figcaption>Sex imbalance in <a href="/wiki/Bahrain" title="Bahrain">Bahrain</a> caused by policies that restrict female spouses and children of immigrant workers</figcaption></figure> Some countries have a significant disparity between males and females in their population. As stated above, males usually exceed females at birth but subsequently experience different mortality rates due to many possible causes such as differential natural death rates, and increased accidental and violent deaths (including war). Countries with significant imbalances tend to have three characteristics in common. First, a rapid decline in fertility, either because of preference for smaller families or to comply with their nation's population control measures. Second, there is <a href="/wiki/Social_pressure" class="mw-redirect" title="Social pressure">social pressure</a> for women to give birth to sons, often because of a cultural preference for male heirs. Third, families have widespread access to technology to selectively abort female foetuses.<a href="#cite_note-71">[71]</a> Some of the factors suggested as causes of this sex imbalance are <a href="/wiki/Sex-selective_abortion" title="Sex-selective abortion">sex-selective abortion</a> and infanticide, large-scale migration, and behavioral factors statistically linked with sex ratio, such as excessive drinking and violence.<a href="#cite_note-72">[72]</a> Gender imbalance may result in the threat of social unrest, especially in the case of an excess of low-status young males unable to find spouses,<a href="#cite_note-73">[73]</a> and being recruited into the service of militaristic political factions. <a href="/wiki/Economic" class="mw-redirect" title="Economic">Economic</a> factors such as male-majority industries and activities, such as the <a href="/wiki/Petrochemical" title="Petrochemical">petrochemical</a>, <a href="/wiki/Agriculture" title="Agriculture">agriculture</a>, <a href="/wiki/Engineering" title="Engineering">engineering</a>, <a href="/wiki/Military" title="Military">military</a>, and <a href="/wiki/Technology" title="Technology">technology</a> industries, have also contributed to an imbalance toward males in some areas dependent on these industries.<a href="#cite_note-74">[74]</a> One study<a href="#cite_note-75">[75]</a> found that the male-to-female sex ratio in the German state of Bavaria fell as low as 0.60 after the end of <a href="/wiki/World_War_II" title="World War II">World War II</a> for the most severely affected age cohort (those between 21 and 23 years old in 1946). This same study found that out-of-wedlock births spiked from approximately 10–15% during the inter-war years up to 22% at the end of the war. This increase in out-of-wedlock births was attributed to a change in the marriage market caused by the decline in the sex ratio. <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Pyramide_Estonie.PNG" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Pyramide_Estonie.PNG/220px-Pyramide_Estonie.PNG" decoding="async" width="220" height="152" class="mw-file-element" data-file-width="902" data-file-height="625"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 152px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Pyramide_Estonie.PNG/220px-Pyramide_Estonie.PNG" data-width="220" data-height="152" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Pyramide_Estonie.PNG/330px-Pyramide_Estonie.PNG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/95/Pyramide_Estonie.PNG/440px-Pyramide_Estonie.PNG 2x" data-class="mw-file-element"> </a><figcaption>Sex imbalance in <a href="/wiki/Estonia" title="Estonia">Estonia</a></figcaption></figure> <a href="/wiki/Qatar" title="Qatar">Qatar</a> has the highest male-to-female ratio, with 2.87 males/female. For the group aged below 15, <a href="/wiki/Sierra_Leone" title="Sierra Leone">Sierra Leone</a> has the lowest female-to-male ratio with 0.96 males/female, and the <a href="/wiki/Georgia_(country)" title="Georgia (country)">Republic of Georgia</a> and the <a href="/wiki/People%27s_Republic_of_China" class="mw-redirect" title="People's Republic of China">People's Republic of China</a> are tied for the highest male-to-female ratio with 1.13 males/female (according to the 2006 <a href="/wiki/CIA_World_Factbook" class="mw-redirect" title="CIA World Factbook">CIA World Factbook</a>). The value for the entire <a href="/wiki/World_population" title="World population">world population</a> is 1.01 males/female, with 1.07 at birth, 1.06 for those under 15, 1.02 for those between 15 and 64, and 0.78 for those over 65.<a href="#cite_note-CIA_Fact_Book-4">[4]</a> Countries on the <a href="/wiki/Arabian_Peninsula" title="Arabian Peninsula">Arabian Peninsula</a> tend to have a 'natural' ratio of about 1.05 at birth but a very high ratio of males for those over 65 (Saudi Arabia 1.14, Arab Emirates 2.73, Qatar 2.84), indicating either an above-average mortality rate for females or a below-average mortality for males, or, more likely in this case, a large population of aging male <a href="/wiki/Guest_workers" class="mw-redirect" title="Guest workers">guest workers</a>.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] Conversely, countries of <a href="/wiki/Northern_Europe" title="Northern Europe">Northern</a> and <a href="/wiki/Eastern_Europe" title="Eastern Europe">Eastern Europe</a> (the <a href="/wiki/Baltic_states" title="Baltic states">Baltic states</a>, <a href="/wiki/Belarus" title="Belarus">Belarus</a>, Ukraine, Russia) tend to have a 'normal' ratio at birth but a very low ratio of males among those over 65 (Russia 0.46, Latvia 0.48, Ukraine 0.52); similarly, <a href="/wiki/Armenia" title="Armenia">Armenia</a> has an above average male ratio at birth (1.17), and a below-average male ratio above 65 (0.67). The latter may be caused by <a href="/wiki/Human_migration" title="Human migration">emigration</a> and higher male mortality as a result of higher Soviet-era deaths; it may also be related to the enormous (by western standards) rate of <a href="/wiki/Alcohol_consumption_in_Russia" class="mw-redirect" title="Alcohol consumption in Russia">alcoholism in the former Soviet states.</a>[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] Another contributory factor is an aging population, given that due to higher differential mortality rates, the ratio of males to females declines with age. In the <a href="/wiki/Evolutionary_biology" title="Evolutionary biology">evolutionary biology</a> of <a href="/wiki/Sexual_reproduction" title="Sexual reproduction">sexual reproduction</a> the <a href="/wiki/Operational_sex_ratio" title="Operational sex ratio">operational sex ratio</a> (OSR), is the ratio of sexually competing males that are ready to mate to sexually competing females that are ready to mate,<a href="#cite_note-CluttonBrock2007-76">[76]</a><a href="#cite_note-Kvarnemo1996-77">[77]</a><a href="#cite_note-Emlen1976-78">[78]</a> or alternatively the local ratio of fertilizable females to sexually active males at any given time.<a href="#cite_note-Emlen1977-79">[79]</a> This is different from the physical <a href="/wiki/Sex_ratio" title="Sex ratio">sex ratio</a> because it does not take into account sexually inactive or non-competitive individuals (individuals that do not compete for mates). </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(5)"><h2 id="Consequences_of_different_sex_ratios">Consequences of different sex ratios</h2> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=21" title="Edit section: Consequences of different sex ratios" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div><section class="mf-section-5 collapsible-block" id="mf-section-5"> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png" class="mw-file-description"><noscript><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png/220px-Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png" decoding="async" width="220" height="180" class="mw-file-element" data-file-width="1112" data-file-height="909"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 180px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png/220px-Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png" data-width="220" data-height="180" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png/330px-Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png/440px-Schnorr_von_Carolsfeld_Bibel_in_Bildern_1860_083.png 2x" data-class="mw-file-element"> </a><figcaption><a href="/wiki/Tribe_of_Benjamin" title="Tribe of Benjamin">Benjaminites</a> seize wives from Shiloh in this 1860 woodcut by <a href="/wiki/Julius_Schnorr_von_Karolsfeld" class="mw-redirect" title="Julius Schnorr von Karolsfeld">Julius Schnorr von Karolsfeld</a>. There were not enough women available for marriage due to the high losses in the <a href="/wiki/Battle_at_Gibeah" class="mw-redirect" title="Battle at Gibeah">Battle at Gibeah</a>.</figcaption></figure> There are several social consequences of an imbalanced sex ratio. It may also become a factor in societal and demographic collapse. For example, the native population of <a href="/wiki/Cusco" title="Cusco">Cusco</a>, Peru at the time of the Spanish conquest was stressed by an imbalance in the sex ratio between men and women.<a href="#cite_note-80">[80]</a> Analyses of how sex ratio imbalances affect personal consumption and intra-household distribution were pioneered by <a href="/wiki/Gary_Becker" title="Gary Becker">Gary Becker</a>, <a href="/wiki/Shoshana_Grossbard-Shechtman" class="mw-redirect" title="Shoshana Grossbard-Shechtman">Shoshana Grossbard-Shechtman</a>,<a href="#cite_note-81">[81]</a><a href="#cite_note-82">[82]</a> and Marcia Guttentag and Paul Secord.<a href="#cite_note-83">[83]</a> High ratios of males have a positive effect on marital fertility and women's share of household consumption, and negative effects on non-marital cohabitation and fertility and women's labor supply. It has been shown that the labor supply of married women in the U.S., over time, varies inversely with the sex ratio.<a href="#cite_note-84">[84]</a><a href="#cite_note-85">[85]</a> One study used 2021 National Archive of Criminal Justice Data and 2016 U.S. Census Bureau data to show the impact of different gender ratios on <a href="/wiki/Violence_against_women" title="Violence against women">men's violence against women</a> in 3165 U.S. cities and counties.<a href="#cite_note-86">[86]</a> The sex ratio ranged from 40% men to 60% men in the data. Rates of violence were lowest in places with a 51% male ratio. For lower and higher proportions of males, the more the ratio deviated from the average, the higher was the violence. </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(6)"><h2 id="See_also">See also</h2> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=22" title="Edit section: See also" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div><section class="mf-section-6 collapsible-block" id="mf-section-6"> <ul><li><a href="/wiki/Gender_parity" title="Gender parity">Gender parity</a></li> <li><a href="/wiki/Operational_sex_ratio" title="Operational sex ratio">Operational sex ratio</a></li> <li><a href="/wiki/Returning_soldier_effect" title="Returning soldier effect">Returning soldier effect</a></li> <li><a href="/wiki/Sex_selection" title="Sex selection">Sex selection</a></li> <li><a href="/wiki/Sex-selective_abortion" title="Sex-selective abortion">Sex-selective abortion</a></li> <li><a href="/wiki/Surplus_women" title="Surplus women">Surplus women</a></li> <li><a href="/wiki/Missing_women" title="Missing women">Missing women</a></li></ul> Countries: <ul><li><a href="/wiki/List_of_sovereign_states_by_sex_ratio" title="List of sovereign states by sex ratio">List of sovereign states by sex ratio</a></li> <li><a href="/wiki/Lost_boys_(Mormon_fundamentalism)" title="Lost boys (Mormon fundamentalism)">Lost boys (Mormon fundamentalism)</a></li> <li><a href="/wiki/Missing_women_of_China" class="mw-redirect" title="Missing women of China">Missing women of China</a></li> <li><a href="/wiki/List_of_Chinese_administrative_divisions_by_sex_ratio" title="List of Chinese administrative divisions by sex ratio">List of Chinese administrative divisions by sex ratio</a></li> <li><a href="/wiki/List_of_states_and_union_territories_of_India_by_sex_ratio" title="List of states and union territories of India by sex ratio">List of states and union territories of India by sex ratio</a></li></ul> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(7)"><h2 id="References">References</h2> <a role="button" href="/w/index.php?title=Human_sex_ratio&action=edit&section=23" title="Edit section: References" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> edit </a> </div><section class="mf-section-7 collapsible-block" id="mf-section-7"> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output 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China's sex ratio at birth was 118.08 males for every 100 females in 2010, according to census data, Li said." </li> <li id="cite_note-66"><a href="#cite_ref-66">^</a> <a rel="nofollow" class="external text" href="http://www.census2011.co.in/p/glance.php">India at Glance – Population Census 2011 – Final</a> Census of India, Government of India (2013) </li> <li id="cite_note-67"><a href="#cite_ref-67">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMesle,_FranceVallin,_JacquesBadurashvili,_Irina2007" class="citation book cs1">Mesle, France; Vallin, Jacques; Badurashvili, Irina (2007). <a rel="nofollow" class="external text" href="http://www.cicred.org/Eng/Publications/pdf/BOOK_singapore.pdf#page=85">A Sharp Increase in Sex Ratio at Birth in the Caucasus. Why? How?</a> (PDF). Committee for International Cooperation in National Research in Demography. pp. 73–89. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-2-910053-29-1" title="Special:BookSources/978-2-910053-29-1"><bdi>978-2-910053-29-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+Sharp+Increase+in+Sex+Ratio+at+Birth+in+the+Caucasus.+Why%3F+How%3F&rft.pages=73-89&rft.pub=Committee+for+International+Cooperation+in+National+Research+in+Demography&rft.date=2007&rft.isbn=978-2-910053-29-1&rft.au=Mesle%2C+France&rft.au=Vallin%2C+Jacques&rft.au=Badurashvili%2C+Irina&rft_id=http%3A%2F%2Fwww.cicred.org%2FEng%2FPublications%2Fpdf%2FBOOK_singapore.pdf%23page%3D85&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHuman+sex+ratio" class="Z3988"> </li> <li id="cite_note-68"><a href="#cite_ref-68">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAndersonSilver1986" class="citation journal cs1">Anderson, Barbara A.; Silver, Brian D. 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Population and Development Review. 12 (4): 705–37. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F1973432">10.2307/1973432</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/1973432">1973432</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Population+and+Development+Review&rft.atitle=Infant+Mortality+in+the+Soviet+Union%3A+Regional+Differences+and+Measurement+Issues&rft.volume=12&rft.issue=4&rft.pages=705-37&rft.date=1986&rft_id=info%3Adoi%2F10.2307%2F1973432&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F1973432%23id-name%3DJSTOR&rft.aulast=Anderson&rft.aufirst=Barbara+A.&rft.au=Silver%2C+Brian+D.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHuman+sex+ratio" class="Z3988"> </li> <li id="cite_note-69"><a href="#cite_ref-69">^</a> For example, the number of births reported to family planning and other administrative agencies has been significantly lower than the number determined in population surveys and the census. See Zhang, Guangyu (April 2004) <a rel="nofollow" class="external text" href="http://paa2004.princeton.edu/papers/40283">"Very Low Fertility in China in the 1990s: Reality or An Illusion Arising from Birth Underreporting?"</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210705080752/https://paa2004.princeton.edu/papers/40283">Archived</a> 5 July 2021 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a> Paper presented at the annual meeting of the Population Association of America. </li> <li id="cite_note-70"><a href="#cite_ref-70">^</a> For studies reveal underreporting or delayed reporting of female births in China, see <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMerliRaftery1990" class="citation journal cs1">Merli MG, Raftery AE (February 1990). <a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F2648100">"Are births underreported in rural China? Manipulation of statistical records in response to China's population policies"</a>. Demography. 37 (1): 109–26. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F2648100">10.2307/2648100</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/2648100">2648100</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/10748993">10748993</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:41085573">41085573</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Demography&rft.atitle=Are+births+underreported+in+rural+China%3F+Manipulation+of+statistical+records+in+response+to+China%27s+population+policies&rft.volume=37&rft.issue=1&rft.pages=109-26&rft.date=1990-02&rft_id=info%3Apmid%2F10748993&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A41085573%23id-name%3DS2CID&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F2648100%23id-name%3DJSTOR&rft_id=info%3Adoi%2F10.2307%2F2648100&rft.aulast=Merli&rft.aufirst=MG&rft.au=Raftery%2C+AE&rft_id=https%3A%2F%2Fdoi.org%2F10.2307%252F2648100&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHuman+sex+ratio" class="Z3988"> and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCai,_YongLavely,_William2003" class="citation journal cs1">Cai, Yong; Lavely, William (2003). <a rel="nofollow" class="external text" href="http://www.excellentfuture.ca/sites/default/files/China's%20Missing%20Girls_0.pdf">"China's Missing Girls: Numerical Estimates and Effects on Population Growth"</a> (PDF). The China Review. 3 (2): 13–29. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/23461902">23461902</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+China+Review&rft.atitle=China%27s+Missing+Girls%3A+Numerical+Estimates+and+Effects+on+Population+Growth&rft.volume=3&rft.issue=2&rft.pages=13-29&rft.date=2003&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F23461902%23id-name%3DJSTOR&rft.au=Cai%2C+Yong&rft.au=Lavely%2C+William&rft_id=http%3A%2F%2Fwww.excellentfuture.ca%2Fsites%2Fdefault%2Ffiles%2FChina%27s%2520Missing%2520Girls_0.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHuman+sex+ratio" class="Z3988"> </li> <li id="cite_note-71"><a href="#cite_ref-71">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJian_Lee,_DeborahSubramanian,_Sushma2011" class="citation web cs1">Jian Lee, Deborah; Subramanian, Sushma (15 November 2011). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20161130190334/http://pulitzercenter.org/reporting/china-gao-po-bachelor-women-marriage-economy">"A Single Man: One Chinese Bachelor's Search for Love"</a>. Pulitzer Center on Crisis Reporting. Archived from <a rel="nofollow" class="external text" href="http://pulitzercenter.org/reporting/china-gao-po-bachelor-women-marriage-economy">the original</a> on 30 November 2016. Retrieved 19 December 2011.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=A+Single+Man%3A+One+Chinese+Bachelor%27s+Search+for+Love&rft.pub=Pulitzer+Center+on+Crisis+Reporting&rft.date=2011-11-15&rft.au=Jian+Lee%2C+Deborah&rft.au=Subramanian%2C+Sushma&rft_id=http%3A%2F%2Fpulitzercenter.org%2Freporting%2Fchina-gao-po-bachelor-women-marriage-economy&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHuman+sex+ratio" class="Z3988"> </li> <li id="cite_note-72"><a href="#cite_ref-72">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBauer2015" class="citation news cs1">Bauer, David (January 2015). <a rel="nofollow" class="external text" href="http://qz.com/335183/heres-why-men-on-earth-outnumber-women-by-60-million/">"A story of drinkers, genocide and unborn girls"</a>. Quartz.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Quartz&rft.atitle=A+story+of+drinkers%2C+genocide+and+unborn+girls&rft.date=2015-01&rft.aulast=Bauer&rft.aufirst=David&rft_id=http%3A%2F%2Fqz.com%2F335183%2Fheres-why-men-on-earth-outnumber-women-by-60-million%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHuman+sex+ratio" class="Z3988"> </li> <li id="cite_note-73"><a href="#cite_ref-73">^</a> <a href="/wiki/Valerie_M._Hudson" title="Valerie M. Hudson">Hudson, Valerie M.</a> and den Boer, Andrea M. (2004) Bare Branches: The Security Implications of Asia's Surplus Male Population. 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The Boston Globe.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Boston+Globe&rft.atitle=A+singles+map+of+the+United+States+of+America&rft.date=2008-03-30&rft.aulast=Florida&rft.aufirst=Richard&rft_id=http%3A%2F%2Fwww.boston.com%2Fbostonglobe%2Fideas%2Farticles%2F2008%2F03%2F30%2Fa_singles_map_of_the_united_states_of_america%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHuman+sex+ratio" class="Z3988"> </li> <li id="cite_note-75"><a href="#cite_ref-75">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKvasnickaBethmann2007" class="citation web cs1">Kvasnicka, Michael; Bethmann, Dirk (1 October 2007). <a rel="nofollow" class="external text" href="http://econ.korea.ac.kr/~ri/WorkingPapers/W0730.pdf">"World War II, Missing Men, and out-of-wedlock childbearing"</a> (PDF). 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hreflang="ar" data-title="نسبة الجنس البشري" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target">العربية</a></li><li class="interlanguage-link interwiki-ban mw-list-item"><a href="https://ban.wikipedia.org/wiki/S%C3%A9ks_rasio_manusa" title="Séks rasio manusa – Balinese" lang="ban" hreflang="ban" data-title="Séks rasio manusa" data-language-autonym="Basa Bali" data-language-local-name="Balinese" class="interlanguage-link-target">Basa Bali</a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%AE%E0%A6%BE%E0%A6%A8%E0%A6%AC_%E0%A6%B2%E0%A6%BF%E0%A6%99%E0%A7%8D%E0%A6%97%E0%A6%BE%E0%A6%A8%E0%A7%81%E0%A6%AA%E0%A6%BE%E0%A6%A4" title="মানব লিঙ্গানুপাত – Bangla" lang="bn" hreflang="bn" data-title="মানব লিঙ্গানুপাত" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target">বাংলা</a></li><li class="interlanguage-link interwiki-bh mw-list-item"><a href="https://bh.wikipedia.org/wiki/%E0%A4%B2%E0%A4%BF%E0%A4%82%E0%A4%97%E0%A4%BE%E0%A4%A8%E0%A5%81%E0%A4%AA%E0%A4%BE%E0%A4%A4" title="लिंगानुपात – Bhojpuri" lang="bh" hreflang="bh" data-title="लिंगानुपात" data-language-autonym="भोजपुरी" data-language-local-name="Bhojpuri" class="interlanguage-link-target">भोजपुरी</a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%86%D8%B3%D8%A8%D8%AA_%D8%AC%D9%86%D8%B3%DB%8C_%D8%A7%D9%86%D8%B3%D8%A7%D9%86%DB%8C" title="نسبت جنسی انسانی – Persian" lang="fa" hreflang="fa" data-title="نسبت جنسی انسانی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target">فارسی</a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Sexe-ratio_chez_l%27%C3%AAtre_humain" title="Sexe-ratio chez l'être humain – French" lang="fr" hreflang="fr" data-title="Sexe-ratio chez l'être humain" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target">Français</a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%B2%E0%A4%BF%E0%A4%82%E0%A4%97%E0%A4%BE%E0%A4%A8%E0%A5%81%E0%A4%AA%E0%A4%BE%E0%A4%A4" title="लिंगानुपात – Hindi" lang="hi" hreflang="hi" data-title="लिंगानुपात" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target">हिन्दी</a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Rasio_jenis_kelamin_manusia" title="Rasio jenis kelamin manusia – Indonesian" lang="id" hreflang="id" data-title="Rasio jenis kelamin manusia" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target">Bahasa Indonesia</a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A7%D0%BE%D0%B2%D0%B5%D0%BA%D0%BE%D0%B2_%D0%BF%D0%BE%D0%BB%D0%BE%D0%B2_%D1%81%D0%BE%D0%BE%D0%B4%D0%BD%D0%BE%D1%81" title="Човеков полов сооднос – Macedonian" lang="mk" hreflang="mk" data-title="Човеков полов сооднос" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target">Македонски</a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%B8%E0%B5%8D%E0%B4%A4%E0%B5%8D%E0%B4%B0%E0%B5%80%E0%B4%AA%E0%B5%81%E0%B4%B0%E0%B5%81%E0%B4%B7%E0%B4%BE%E0%B4%A8%E0%B5%81%E0%B4%AA%E0%B4%BE%E0%B4%A4%E0%B4%82" title="സ്ത്രീപുരുഷാനുപാതം – Malayalam" lang="ml" hreflang="ml" data-title="സ്ത്രീപുരുഷാനുപാതം" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target">മലയാളം</a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%AE%E0%A8%A8%E0%A9%81%E0%A9%B1%E0%A8%96%E0%A9%80_%E0%A8%B2%E0%A8%BF%E0%A9%B0%E0%A8%97_%E0%A8%85%E0%A8%A8%E0%A9%81%E0%A8%AA%E0%A8%BE%E0%A8%A4" title="ਮਨੁੱਖੀ ਲਿੰਗ ਅਨੁਪਾਤ – Punjabi" lang="pa" hreflang="pa" data-title="ਮਨੁੱਖੀ ਲਿੰਗ ਅਨੁਪਾਤ" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="Punjabi" class="interlanguage-link-target">ਪੰਜਾਬੀ</a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%D8%A7%D9%86%D8%B3%D8%A7%D9%86%DB%8C_%D8%AC%D9%86%D8%B3%DB%8C_%D8%AA%D9%86%D8%A7%D8%B3%D8%A8" title="انسانی جنسی تناسب – Western Punjabi" lang="pnb" hreflang="pnb" data-title="انسانی جنسی تناسب" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target">پنجابی</a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/%C4%B0nsanlarda_cinsiyet_oran%C4%B1" title="İnsanlarda cinsiyet oranı – Turkish" lang="tr" hreflang="tr" data-title="İnsanlarda cinsiyet oranı" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target">Türkçe</a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%A1%D1%82%D0%B0%D1%82%D0%B5%D0%B2%D0%B0_%D1%81%D1%82%D1%80%D1%83%D0%BA%D1%82%D1%83%D1%80%D0%B0_%D0%BD%D0%B0%D1%81%D0%B5%D0%BB%D0%B5%D0%BD%D0%BD%D1%8F" title="Статева структура населення – Ukrainian" lang="uk" hreflang="uk" data-title="Статева структура населення" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target">Українська</a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%A7%D9%86%D8%B3%D8%A7%D9%86%DB%8C_%D8%AC%D9%86%D8%B3%DB%8C_%D8%AA%D9%86%D8%A7%D8%B3%D8%A8" title="انسانی جنسی تناسب – Urdu" lang="ur" hreflang="ur" data-title="انسانی جنسی تناسب" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target">اردو</a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E4%BA%BA%E9%A1%9E%E6%80%A7%E5%88%A5%E6%AF%94" title="人類性別比 – Chinese" lang="zh" hreflang="zh" data-title="人類性別比" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target">中文</a></li></ul> </section> </div> <div class="minerva-footer-logo"><img src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" alt="Wikipedia" width="120" height="18" style="width: 7.5em; height: 1.125em;"/> </div> <ul id="footer-info" class="footer-info hlist hlist-separated"> <li id="footer-info-lastmod"> This page was last edited on 20 October 2024, at 01:59 (UTC).</li> <li id="footer-info-copyright">Content is available under <a class="external" rel="nofollow" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">CC BY-SA 4.0</a> unless otherwise noted.</li> </ul> <ul id="footer-places" class="footer-places hlist 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