Doctoral Dissertation Improvement: Maternal reproductive trade-offs and the duration of exclusive breastfeeding in a natural fertility population

国际卫生组织建议在生命的前6个月进行纯母乳喂养，以促进婴儿的最佳发育，并降低感染疾病的风险。然而，在全球范围内，纯母乳喂养6个月的情况相对罕见--包括在许多传染性疾病发病率较高的欠发达人口中。对于许多母亲来说，6个月前补充喂养的风险可能并不明显，或者可能会被相互竞争的时间和精力需求所抵消。这项研究将考察处于经济边缘地位的玻利维亚齐曼族婴儿喂养模式和相关结果的差异。这项由博士生梅勒妮·马丁(加州大学圣巴巴拉分校)在迈克尔·古尔文博士的指导下进行的研究，检验了产妇工作和育儿需求减少纯母乳喂养时间这一假设。此外，由于哺乳母亲体重迅速减轻，而且不会来月经，Tsimane母亲可能会在6个月前引入补充食物，以最大限度地减少哺乳的卡路里损失。这种补偿可以使产后保持体重并提早恢复月经。齐曼妇女无法获得避孕药具；因此，早期补充喂养可能有助于齐曼母亲的高生育率(平均9个孩子)。研究人员将对齐曼的母亲进行调查，以确定纯母乳喂养的长度是否会随着婴儿状况、产妇的年龄和状况、产妇的工作和育儿需求而变化。研究人员还将前瞻性地收集Tsimane母亲和婴儿的饮食、行为和生物数据，以检查补充喂养模式如何影响母亲的能量、月经状况、婴儿生长和发病率。这项研究将考察当地的信仰和齐曼族母亲对婴儿健康、生长和发育的看法如何进一步影响喂养决定。结果将有助于制定战略，促进文化上可接受的婴儿喂养做法，从而最大限度地有利于孕产妇和婴儿健康。

International health organizations recommend exclusive breastfeeding for the first 6 months of life to promote optimal infant growth and reduce risk of infectious illness. Globally, however, exclusive breastfeeding for 6 months is relatively rare - including in many less developed populations with high rates of infectious disease. For many mothers, the risks associated with complementary feeding before 6 months of age may not be apparent, or may be outweighed by competing time and energy demands. This study will examine differences in infant feeding patterns and associated outcomes in an economically marginalized population, the Tsimane of Bolivia.This research by doctoral student Melanie Martin (University of California, Santa Barbara), under the supervision of Dr. Michael Gurven, tests the hypothesis that maternal work and childcare demands reduce the length of exclusive breastfeeding. Furthermore, because nursing mothers rapidly lose weight and do not menstruate, Tsimane mothers may introduce complementary foods before 6 months of age to minimize the caloric losses of nursing. This offset may enable postpartum weight maintenance and earlier resumption of menstruation. Tsimane women do not have access to contraceptives; early complementary feeding may therefore contribute to Tsimane mothers' high fertility rates (average 9 children). The researchers will survey Tsimane mothers to determine if the length of exclusive breastfeeding varies with infant condition, maternal age and condition, and maternal work and childcare demands. Researchers will also prospectively collect dietary, behavioral and biological data from Tsimane mothers and infants to examine how complementary feeding patterns affect maternal energy, menstrual status, infant growth and incidence of illness. The study will examine how local beliefs and Tsimane mothers' perceptions of infant health, growth, and development further influence feeding decisions. Results will aid in devising strategies to promote culturally acceptable infant feeding practices that optimally benefit maternal and infant health.