The demographic trajectory of the sex ratio in human pregnancy

描述（由申请人提供）：尽管经过数百年的推测和一个多世纪的集中研究，对人类性别比例的综合描述和理解仍然难以捉摸。利用人口统计学、经济学、进化生物学和医学的技术和方法，我们将1)分析来自囊胚的数据，以便在受孕后的特定时间对性别比例做出前所未有的估计；2)分析来自绒毛膜-绒毛取样和羊膜穿刺术的数据，以便在怀孕后期的特定时间对性别比例做出准确的估计。3)分析所有已发表的人工流产性别比数据，以及怀孕20周后性别胎儿死亡率的已发表数据，以描述从妊娠早期到新生儿期人类性别比的变化轨迹。我们还将开发理论模型，以了解人口统计学和进化动力学以及与人口性别比偏差相关的平衡，并得出适用于我们数据的可测试预测。更全面地了解人类性别比例的潜在用处是巨大的。特别是，我们对受孕后性别比早期轨迹的分析，将有助于深入了解出生时性别比在多大程度上是由性染色体分离和激素等其他因素决定的，这些因素对环境更不稳定。这个关于人口性别比的研究项目对公共卫生很重要，因为它将帮助我们了解生殖生物学以及家庭和社会环境对性别比的影响程度。这些信息有助于更好地理解美国最近人口趋势的原因和后果。我们将汇集来自人口统计学、进化生物学、医学和统计学的贡献，以便全面了解人类怀孕期间性别比例的变化。

DESCRIPTION (provided by applicant): Despite hundreds of years of speculation and well over a century of focused research, an integrated description and understanding of the sex ratio in humans remains elusive. Using techniques and approaches from demography, economics, evolutionary biology, and medicine we will 1) analyze data derived from blastocysts in order to make an unprecedented estimate of the sex ratio at a defined time just after conception, 2) analyze data from chorionic-villus sampling and from amniocentesis in order to make accurate estimates of the sex ratio at well-defined times later during pregnancy, 3) analyze all published data on the sex ratios of induced abortions as well as published data on sex- specific fetal mortality after twenty weeks of pregnancy in order to describe the trajectory of the human sex ratio from early pregnancy to the neonatal period. We will also develop theoretical models in order to understand the demographic and evolutionary dynamics and equilibria associated with sex ratio biases in human populations and in order to derive testable predictions to apply to our data. The potential usefulness of a fuller understanding of the human sex ratio is substantial. In particular, our analyses of the early trajectory of the post-conception sex ratio will provide insight into the degree to which the sex ratio at birth is determined by sex-chromosome segregation and by other influences such as hormones, which are more environmentally labile. This research project on the sex ratio in human populations is of importance to public health because it will help us understand the degree to which the sex ratio is influenced by the biology of reproduction as well as by the family and social environments. Such information is useful for greater understanding of the causes and consequences of recent demographic trends in the United States. We will bring together contributions from demography, evolutionary biology, medicine, and statistics in order to gain a comprehensive understanding of the changes in the sex ratio during human pregnancy.