Doctoral Dissertation Improvement : Biological and Cultural Factors Associated with Lactational Dysfunction in Overweight Women

对人类生殖生态学的研究为进化如何塑造生殖机制(如排卵、妊娠和哺乳)以适当地应对环境环境提供了关键见解。例如，生理机制降低了已在哺乳或能量储备较低的女性的排卵功能。然而，哺乳在很大程度上不受低能量储存的影响，因为当母体能量被分配时，这一过程被赋予新陈代谢优先。尽管大多数这类研究都集中在营养紧张的人群中，但最近的研究表明，超重的女性面临更高的哺乳功能障碍的比率。与正常体重的女性相比，超重的女性在产后开始哺乳的时间较晚，如果确定了，就会更早停止母乳喂养。从生殖生态学的角度来看，这一结果令人惊讶，因为超重女性有充足的哺乳所需的能量储存，而且通常为哺乳提供新陈代谢优先。尽管研究一直报告母亲肥胖与迟至哺乳和短时间哺乳之间存在关联，但这种关系的原因仍不清楚。这个项目将聚焦于核心问题：为什么超重的女性有患哺乳功能障碍的风险？由于建立和维持牛奶产量的过程依赖于一套精心调整的生理、行为和社会条件，因此这项研究将利用生物文化方法。来自明尼阿波利斯-圣彼得堡的孕妇。保罗将被招募参加一项配对病例对照研究。数据将通过三种方法收集：首先，一项产前调查将调查心理社会和人口因素如何影响母乳喂养，以检验母亲肥胖与这些因素之间的关系。其次，将观察哺乳过程，参与者将记录母乳喂养的尝试以及影响他们决定断奶的因素，以测试行为模式与母亲肥胖的关联。最后，将抽取血清样本来测试肥胖和非肥胖女性之间的荷尔蒙差异。统计分析将确定母亲肥胖、激素浓度、行为模式和心理社会因素对母乳喂养结果的相对贡献。母乳喂养对婴儿和他们的母亲有很多好处。随着全球肥胖率的持续上升，找出这群女性面临哺乳功能障碍风险的原因变得越来越重要。该项目将为公共卫生机构传播超重妇女在尝试母乳喂养时面临的特殊问题的知识奠定基础。阐明这一人群中哺乳功能障碍的原因将有助于解释其他环境和文化背景下的哺乳功能障碍，并将更容易预测导致哺乳性能差的近端机制。最后，这个项目将增进关于现代人类女性如何管理与生殖战略有关的权衡的知识。它将解决这样一个谜题：过剩的(储存的)代谢能量如何干扰生殖所必需的高能量任务的执行。通过这样做，它将有助于理解支持牛奶生产的生理途径如何与脂肪储存和新陈代谢途径相关。

Studies of human reproductive ecology have provided key insights into how evolution has shaped reproductive mechanisms (e.g., ovulation, gestation and lactation) to respond appropriately to environmental circumstances. For example, physiological mechanisms reduce ovulatory function in women already nursing or with low energy stores. Lactation, however, is largely unaffected by low energy stores as this process is given metabolic priority when maternal energy is partitioned. Though most such studies have focused on nutritionally stressed populations, recent research has demonstrated that overweight women face a higher rate of lactational dysfunction. Compared to normal weight women, overweight women establish lactation later postpartum and if established, stop breastfeeding sooner. This result is surprising from a reproductive ecology perspective because overweight women have ample energy stores needed for lactation and because of the metabolic priority generally afforded to lactation. Although studies consistently report an association between maternal obesity and late onset to and short duration of lactation, the causes of this relationship remain unknown. This project will focus on the central question: Why are overweight women at risk for lactational dysfunction? Because the process of establishing and maintaining milk production depends upon a finely tuned set of physiological, behavioral and social conditions, this research will utilize a bio-cultural approach. Pregnant women from Minneapolis-St. Paul will be recruited to participate in a matched-pair case-control study. Data will be collected using three methods: First, a prenatal survey will investigate how psychosocial and demographic factors influence breastfeeding to test the relationship between maternal obesity and these factors. Second, nursing episodes will be observed and participants will record attempts to breastfeed as well as factors influencing their decision to wean, in order to test the association of behavioral patterns and maternal obesity. Finally, serum samples will be drawn to test hormonal differences between obese and non-obese women. Statistical analyses will identify the relative contribution of the effects of maternal obesity, hormone concentrations, behavioral patterns and psychosocial factors on breastfeeding outcomes.Breastfeeding provides numerous benefits for infants and their mothers. As obesity rates continue to rise globally, it becomes increasingly important to uncover the reasons why this cohort of women is at risk for lactational dysfunction. This project will lay the groundwork for knowledge that can be used by public health institutions to disseminate information on the special problems overweight women face when attempting to breastfeed. Elucidating the causes of lactational dysfunction in this population will help to explain lactational dysfunction in other environmental and cultural contexts and will make it easier to predict the proximate mechanisms leading to poor lactation performance. Finally, this project will advance knowledge regarding how modern human females manage trade-offs relating to reproductive strategies. It will address the puzzle of how a surplus of (stored) metabolic energy can interfere with the performance of an energetically demanding task essential for reproduction. In doing so, it will contribute to the understanding of how physiological pathways supporting milk production relate to pathways of fat storage and metabolism.