CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "catalog.aap.org",cType: 'managed',cRay: '8e70f3e3d99bcdfa',cH: 'F7ILBGLa55m1Nj6d41vRTb1ZR7AqJqEuaJJdC0UBHrI-1732362742-1.2.1.1-xBHUjRNGeGnGJkRYEMD5j7yMY5Gg9.yTSuoxSJNOFJdQ_3fHp5Z_tPY5XSJMR5hz',cUPMDTk: "\/?__cf_chl_tk=Qx4vUs82sRvtHe0.zVihlJvv5Jt3lZ4gRX1L9hCpCN4-1732362742-1.0.1.1-Via5MpzpsFGgWc2j4OTK_YAqRl64V2Eeq5abyHrd34Q",cFPWv: 'g',cITimeS: '1732362742',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/?__cf_chl_f_tk=Qx4vUs82sRvtHe0.zVihlJvv5Jt3lZ4gRX1L9hCpCN4-1732362742-1.0.1.1-Via5MpzpsFGgWc2j4OTK_YAqRl64V2Eeq5abyHrd34Q",md: "8uaQabWGG_vn4V4vr3.SSWPnMejWTszR378JR5khtpc-1732362742-1.2.1.1-aR3VHLpKIhldV.WZQ.8KK4Zbv3zrpjvVE.T7dwTod1qRt042ci3DXKADvzWwYIyikpGrZMR2o3E9wWUQUm1NP5j4Q5L2HP162pHUo.VuN._ZAckAs8QEH2d5ebZvzq9IXLPkkAgN2FGaTq6ZbIeqsSlYLgzFXcWPHAAh9b0I_BDBHrgTKBLpc3CxPcbxOM5mMai57NJUvq_QMmN0Zjviwqyz_dZktiOft7jGmJwMfHYTX2qQwCrwA1.osy5nFJ7K1kAWfl1BsnuJQlSlyHYzVFA1HGrpugAKO_X8Y9im0Z42aFvYrQjC6JJDkYoWeX4yGXEp255zmVVSKZvT4Y3FlRnf.pDAOPPcW.dFKuZ3YcgLx89fqefU6EKgJlZb6Si975faF1pkrxeKBrO2Dkb57PbJffZdM75JATq5pBfIAFpNumgjKbeIoxgeKlnETvnmJBswJwKFkgQnWhLoLNotOmgYyOa3wQj7SYFVtCxZ2ZRxztXqzJzUwmXAA64Sd4jxzRcbfGt3wPwVF24Xuo8kLyE5e4fSpiBW0F9nxisse2hmWSfVj7YKnQVRYiJ0Q63N_dlp51zFnuhLel8DhaaEFvhuvJ69sJqSX.AfKKQ7FfBVQferSOOd86hnf7HU801wFpHjqmKGLhgCFrsfILZcejaiqapX5hk1PXR0Eze.uZyx1jGPyX6XIsZuMBWNMyrGJv7KazzoHNwWDWbbqR.6GPA57VoyRgQgMBSRCCwjkrdrYDoHiobJWhZAWjgL2gEXybaA2xfeIQ9c.y7HJBaqtu6WdXIf7ylhXb9oGMcdlKTS7i2oJedbbN5puuAHM66LQEUNZndqo1J45b11WcWzQo2vVrXtqlnws.K6m2DibIMjsW4QZl53069N9KQkJWGapt0la5vyFEkOF0Yth4vASIbvbI80MJWAdB52TrGg94qf9hbpYG6iZxU35ie3Q6nH07rfQNwZNE0T7_rPROKglV4PzjgaFg9Sf25HMspGx.MlCmblzQsMbwgFRQMUYIkYDICV3iWv7BtIqjLOEySoo9_.nhzikdBSP9q24uFOZXkTvFRU0OL6vfp3Wf_kANhGMy74LUmMDqIOYNPCcYg7eg7iorLwDXjxIDEJFVXBR8pGR9USXv59uSUYcjXAOp.yAa8etEolnmVg1Z6EZxZNhoEZp.V8fXxtVCFEfN8RgZyH99FbWiZXkYZR1Tvx33yacDNXjTO0EtBwjmk3Djr7T1JHjRiLkOYfjSJwFf1E2p9rDbwrQhnc6sQaESlx7DPGx26NtOSQ.mMQxbOgUszEiP9w69IHLPJbBKGHljpJSvGM5ZiKfPNCl0uCLVF5TF9IvkbtkY.A8t21B57CUzgSV7jQftK7hTuDAItPpYIAlmn1wUdcMxZoqCpwU3zXWOmqC.jrJ3_VHY5vrQ4VeAERq3SS.ys2XLWI6l6Ky7QFNEC5Y6I.ou61loXypw33YwrMgn_nMqWhCDu5aHJhwMYI5og2yZiRhcZkUlWy7urVApT2Gch2QA.NjX2wJNON6nbh3UB6b1R6iq3HEkT4i2VPyrZgsoPt1nt1rrLM.xNBcK.weR7RAemAEpR1vmTiDL890pvA9P2wL_WJJMCzMrjWmLFRzHl4usll15TNRl6zoUYhWFmJ72V87GK1fuafQWYWryHaW7EV0MA9mp_phurogBw16MpOpLBlGUzH5jTtvw74o3EbOa7XbD.nt3HH8E56ByHNSiMw_gD0JQ4.GKDwih6ObmpYc0.VQcX49PawZSAQXz9KiJfbU86TqDR2f8fsgvrXObt574panpvI9bL_XPUZ7BruIbBA7RsehhlWrstuSfeoNK2IxAsAtlO30Oh42RsgyI_u0xrW8k3lxgtYlB2Y0syNzpcTwpdIPIpDdx_QnV4ZiBWKFeWCbRHGeMPYmM1p0u_7WbYVgAEdeXiugNRGVNxdceEOXBP6e4mdw5zrrfDFuqSHjPyPplUuqY69caIi7_8TVAkuGaVZ07y_MQNOHUpj8GNIRgtv_NCceu3V.Uzufc9kIPI9grSpALcpINIbS03kGUjdY4L2e9stFBDFewcxFkFUkJpGVdUUVJ7nD5MwLWM_xpeUU2_7QKda6SYyXriw2vTBXb15H2_xyqmuWCTyWclSKsFbRQPx8sui8GQ1TMZAU9M5P0.5.4ZeM6VYJRG4qsn2TVZ78xAHGM6INtSrxGssCVINL.wknKCIh65YNpNeeMQCo5M05XX.jLUPE9ID9fYfafi6tolHMidprAzsfXOyVoZB7TGap2Q5akJqhAgrZIW25PTijcA79z8JOFHkcHomp6x0FFpCOGsXkHWq2X6WKmMvoJjpataQ5b3g5JE096Rs2zSinSCHTYF0b_0e957kKN2FLBUmf2HxJFrdb0nDDoP6BiSBpgVnR7VZZIgzL1YDkTVu5Duyjfyg_0ZbUNNv41Pd_u8FXIb2FAnFnA93LZdNi4zwShMA3pHG7YsrOC3pU6NVoXOPsEXZlRZF4PqOyxsWZ8rBryuiqTlfDXQQ5KjrQzoCnSaPZ66_OLLq4LMXxmekOiavluTD8tpUCP02iPkmoNDmf0mWmBfnPz8O_RZoiuG3pzaI7As9Ndmtwkv.nipvv2j3KWsKmJLlgb52kYExWXKgiAVSxPdtjY783aA_Lo8nqFmgGFxUvAXc2YARb.Zy_1CiZbYV6hEUtGrGyulS02qIvQi_gPZXaszH00M53UlkXjap9grarA6icqrm8_yOe9HM2htDCWmGHDmrr4vDVOeOAFr02U2h7v9qSDQwJ2bqY4Ae73dy6rjm9EI9XWYDSY.nczYdxUfYWJ9OanRtneBVhXMTQvOkrcp3zsGrULSvNkQw3gWfqCsfezVNZfaWP5k1",mdrd: "dfOL5DT9uT7KqE0qHOYa9BsENpGgEAHQUiZxk0pk7IQ-1732362742-1.2.1.1-5V0ZPqWVkTiV6.gQJvuldBEimOIPEfvRnFBmew2M09k0NxRoA7I5k0HjJor_rZmLovZ8806wLEac19K9r9sIQz05ZRf6xXXZu8q4s17afEVy.DdPdCUKiWVM.rsRM5CVWWEssVa0ccf7srhCrXuhVZRj3D9d01T7I_eaJLbU0FvoK1B94JXchIKxvDBamXyuNCGDgE.62Ytxj_XtxFiYG9tdk5qCifx_08Oa2DKYHPrvfNX_a6qyEvC9dtgP5BQLm6UMoYIWMA5ZRczXtXRuIFsPwCoBseL0ZtHIBYdB5hhuVYHAvYeqpedzcz8D3xf901lYhcgtr1Ghp6eAxyWUcY_Ope.K5ziYMfd4OeTAxHyOGR0HbGQX4b9ddlCimijUHu15vCTTy9sgryJtHBJAwUy0228MW5X1dyo9gp3KkjvpeYYF0M2hY4g4b_I8gMCyFxKiZis.PJ356TFBy_GweMQ1MPBus3sBDgKOQaHvCFENdaIriRcrQKmHaNp4SLWC6UYY3tBMhLwIxig_jBr9gjFDiwbld1bdDVUQ93fWj4NuKwwZz3xAlNSlpzdc_5KLyUwDm9880moF1F.UIsNlslvcpZkvdfR84r8RkbmhpikpIHyQeeW9CD22Quizcb1dmp0.u4e8HFv4Faod7pnaZnIL7jtSZPLCyJZ.K0INC120jGDXiA41WGuws7jhTA8xdGSPUpfi3YL5saCdCeEYQg._rYCODLB3rdH8wr7Ob_tbgatgPHe7I2.bk9qpRCDVMTInmW98fo4zGdX8ik6w23YTmlO83zKtC6PS.hJszFoLi1H7yZa_jue.7.9HDFYFI2R4Y.aE0ntaDKASCjgoAhYqCdqIygDmm43IFbeMV.jRaMTs1nFjflDNrK8EcXrz7828t92MKCyxFJpjmSDw7QYhhS34q_U6ofg3e4i5gKwURSCnhvHqWTU0wu8OJI4FFKbnJ0pKGzGuIEXXmXnpzX0dLbVRYaAxm_22ai6N1Yo_kYgKtee6bjju8V0vRJrXSxB3qtbbQLyJWmSKeEyrDLdVpuHjmwo_7goTg2A8Lpl5sHLd5qs56yQmlp4v8ls.tEJl7UGy5BiuvuMt15LlgbHnRNlXQySqVaZbRjZVAUxO9GLJmgK5BsQRxaqkbaJWK79QPyGgNJSfVjrHVeUi3qzQTAc4kgdz1uZnTuPQo4T1RAlP4baTEXlS6y7xQq0HtflisRhbRlylYqFLYk0YIRi5P3pWpBmI8ufjjz.xLTSoBiYgbPKDTtQBemqdvAmyejnAP75u.5puCLg2kpYzczSO22nGNGKNd.r4vACPN3R1JxdSK1Kmb13pd_il5SFgcdX59E0mned4_sAlR90GGXj80doxOnnLDY8x7BEgXHM09wffcHab0SJ81Iv7kFQjNUdqPPghM0Kgyet_Po2toOvjLRMp9166i28wd1tlTXbp5htcDrwxddGfig17wlRXGlmX5BUkVjxsk.U2R61nG.L8ms51s80RzDNjB.vt2lodQB_edJKrezBovHXgC3UdyVoRuC7J.FnE5wzIXQjKzb_jcT0PluJbjB0YJNHHLqRQz1eecPfrFK03_Y2Idehk4FzhK7Ky2UYXAE4HPuLfBwofQCzHY.92IEZYh33g18rlt7odSIAehDF7FbOa9pckmusc_PfRqN.Luhg4ZMwPUvtpkRnvCTez2bRnClJP9wNay.q3C8nbXunjn.ZugWNuc8ZDw_oFPOT72J.YhxzThIVu8hh7XzlhTjS.wktjRNSl4yM40V1JphmcUlVlkLGghu_N3CX7DP4.Hqw0IKk.Ev_xf1xjj3hqckSITTp7_Aq426LsgqWJ4rvADhisRzrFKbihajsxVIhCAtO3xPe_lNoCbKvOpCKNixNOg4vVVW22BmEqPlEq9vfuq2rQY4Y3hP9Iq00OYGi15q79fGi9_3LRA.htcLYcbk9wgdflkaEjEAlQFRMjfNObRTQIaa.3"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=8e70f3e3d99bcdfa';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/?__cf_chl_rt_tk=Qx4vUs82sRvtHe0.zVihlJvv5Jt3lZ4gRX1L9hCpCN4-1732362742-1.0.1.1-Via5MpzpsFGgWc2j4OTK_YAqRl64V2Eeq5abyHrd34Q" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>