Doctoral Dissertation Research: Seasonality of Fertility in the Laguna de Sinamaica, Venezuela

几乎在所有人类群体中都观察到了季节性出生模式。虽然这种模式在许多动物物种中都是已知和理解的，但在人类身上很难分析，因为导致出生率的生物因素和文化因素被混淆了。总体而言，许多关于人类出生季节性的研究得出的结论是，尽管这种季节性变化是普遍的，但变化的原因并不是普遍的。大多数试图解释在特定人群中观察到的季节性模式的研究只集中在几个可能的原因上。在许多情况下，饮食、工作量和气候等因素被证明与生育力有关，但它们与生育力之间的联系机制仍未得到解释。这项拟议的研究将分析美国本土人口(委内瑞拉西北部的Anu人)的季节性出生模式。它将描述生育力的近期决定因素的季节性变化，包括卵巢周期和胎儿丧失的特征。这些数据将被用于描述生育能力和胎儿丧失的模型，这些模型共同描述生育的季节性。这项研究包括对1346个尿样的分析，这些尿样是在怀孕最多和最少的季节每周收集两次。这些样本将被检测以确定人类绒毛膜促性腺激素(表明怀孕的激素)以及尿液中雌激素和孕酮的代谢产物的水平；然后，检测数据将与访谈数据一起用于确定排卵周期的比例、周期的长度、受孕率、胎儿丢失率和孕酮水平，作为黄体充足的指标。以前对生育率季节性的调查主要是基于被研究人群特有的因素。这项拟议的研究使用了一个生育率的季节性模型，该模型可以应用于人口稀少。通过结合现有的受孕能力和胎儿丧失模型，可以比以前的研究更彻底地分析生育力的个体近似性决定因素对季节性生育模式的影响。关于更远端决定因素的季节性数据，如饮食、工作量、配偶缺勤和营养状况，可以通过关于最近决定因素的信息进行评估，揭示可能的联系机制，并为进一步研究开辟道路。

Seasonal birth patterns have been observed in virtually all humanpopulations. While such patterns are known and well understood in manyanimal species, they are difficult to analyze in humans, since biologicalfactors contributing to birth rates are confounded with cultural factors.Taken as a whole, the conclusion of the many studies on birth seasonalityin humans is that while such seasonal variation is universal, the causes ofvariation are not universal. Most of the research that has attempted toexplain observed seasonal patterns in specific populations has focused ononly a few possible causal factors. In many cases factors such as diet,workload, and climate are shown to be correlated with fertility, but themechanisms linking them with fertility remain unexplained. The proposed study will analyze seasonal birth patterns in an indigenousAmerican population (the Anu of northwestern Venezuela). It will describeseasonal variation in proximate determinants of fertility, includingcharacteristics of ovarian cycles and fetal loss. These data will be usedin models of fecundability and fetal loss that together describeseasonality of fertility. The study includes analysis of 1346 urinesamples that were collected twice weekly during the seasons of most andfewest conceptions. The samples will be assayed to determine levels ofhuman chorionic gonadotropin (the hormone that indicates pregnancy) and ofurinary metabolites of the hormones estradiol and progesterone; the assaydata then will be used with interview data to determine proportion ofcycles ovulatory, length of cycles, rates of conception, rates of fetalloss, and levels of progesterone, as an indicator of luteal sufficiency. Previous investigations of seasonality of fertility have been basedlargely on factors specific to the population being studied. The proposedstudy uses a model of seasonality of fertility that can be applied to anypopulation. By combining existing models of fecundability and fetal loss,the impact of individual proximate determinants of fertility on seasonalfertility patterns can be more thoroughly analyzed than in previousstudies. Seasonal data on more distal determinants, such as diet,workload, spouse absence, and nutritional status, can then be evaluated interms of the information on the proximate determinants, shedding light onpossible linking mechanisms and opening avenues for further research.