Statistical Modeling of Human Fecundity

该项目的动机是在DESPR已经进行和正在进行的各种妊娠研究。这些研究包括纽约州垂钓者队列前瞻性怀孕研究、生理和感知心理社会压力对怀孕时间的影响以及生育和环境（LIFE）研究的纵向调查（PI，G.流行病学分支的Buck Louis）。 生育能力（Gini，1926）被定义为夫妻在月经周期中定期性交而不避孕的受孕概率。生殖流行病学家对人类生育力模型感兴趣，以确定生殖功能障碍的决定因素和原因。也有人怀疑，各种环境因素对人类生育能力产生负面影响。尽管作出了广泛的努力（例如，温伯格和Gladen（1986），Zhou和其他人（1996），Scheike和詹森（1997），Dunson和Zhou（1997），Dunson和斯坦福大学（2005），仅举几例），对生育力数据建模仍然是一项具有挑战性的统计任务。事实上，随着生育能力的建模从人口统计学和基于人口的背景逐步发展到生殖生物学和不孕症的治疗，新的情况强烈呼吁：1）灵活性，因为研究人员收集的信息量越来越大; 2）鲁棒性，因为对估计效果的潜在粗略解释以及由此产生的日常医疗实践中的重要决策。 影响繁殖力的异质性的两个主要来源是生物和行为。这种区别并不排除这两个因素之间的潜在相互作用。例如，女性生育窗口期的长短和男性精子寿命的长短这两个生物学因素都影响着性交方式对受孕概率的影响。一些因素已被研究并证实为生殖能力受损的因素，如高龄或接触有毒物质。然而，大多数生物学异质性仍然无法解释。同样，性交方式对生育能力的影响的解释部分包括与排卵有关的特定日期的性交次数和时间，宫颈粘液的质量和局部避孕药的使用。然而，无法解释的异质性的大小可能至少与协变量的影响一样重要。 Sundaram博士和她的合作者的研究重点是解释在观察生物因素时遇到的各种测量误差，并开发性交模式和繁殖力的联合建模方法，因为假设性交模式是固定的可能不合理，并且它们都有共同的风险因素，如高龄，生育（以前的孩子出生），并可能受到男性和女性的潜在激素水平的影响。部分已完成或处于完成阶段的项目如下：

This project is motivated by various pregnancy studies that have been conducted and are being conducted at DESPR. These include the New York State Angler Cohort Prospective Pregnancy Study, The Impact of Physiologic and Perceived Psychosocial Stress on Time to Pregnancy and the Longitudinal Investigation of Fertility and the Environment (LIFE) Study (PI, Dr G. Buck Louis of Epidemiology Branch). Fecundability (Gini, 1926) is defined as the probability of conception in a menstrual cycle for couples having regular sexual intercourse without contraception. Reproductive epidemiologists are interested in models for human fecundity to identify the determinants and causes of reproductive dysfunction. There is also suspicion that various environmental factors negatively affect the human fertility. Despite extensive efforts (ex., Weinberg and Gladen (1986), Zhou and others (1996), Scheike and Jensen (1997), Dunson and Zhou (1997), Dunson and Stanford (2005) to name a few), modeling fecundability data remains a statistically challenging task. Indeed, as modeling of fecundability stepped from demography and population-based contexts to reproductive biology and treatment of infertility, the new situation created a strong call for: 1) flexibility, because of the important and ever increasing quantity of information researchers collect; and 2) robustness, because of the potential crude interpretations of the estimated effects and the resulting important decisions in everyday medical practice. Two main sources of heterogeneity effecting fecundability are biological and behavioral. This distinction does not preclude potential interactions between these two factors. For example, both womans length of window of fertility and mans length of life of sperm, which are biological factors, modify the effect of intercourse-pattern on the probability of conception. Several elements have been studied and confirmed as factors of impaired fecundability, such as advanced age or exposure to a toxic substance. However, most of the biological heterogeneity remains unexplained. Similarly, the explained part of the effect of intercourse pattern on fecundability includes the number and timing of intercourse on particular days in relation to ovulation, the quality of cervical mucus and the use of local contraceptives. Nevertheless, the magnitude of the unexplained heterogeneity may be at least as important as the effects of the covariates. The research focus of Dr Sundaram and her collaborators are to account for various measurement errors encountered in observing biological factors and to develop joint modeling approach for intercourse pattern and fecundability as assuming the intercourse pattern to be fixed may not be reasonable and they both share common risk factors, like advanced age, parity (previous child birth) and may be influenced by underlying hormonal levels in both male and female. Some of the projects that have been completed or are in completion stage are listed below: