Thesis (Ph.D.) - Indiana University, Anthropology/University Graduate School, 2019In this dissertation, I addressed questions about how maternal ecology affects fetal growth and the hormonal milieu the newborn is exposed to via early postpartum breast milk (colostrum). Drawing on Ramadan fasting as a natural experiment in Rabat, Morocco, I used a biocultural approach and the lens of life history theory to consider how differences between women shape maternal fasting behaviors during late pregnancy and explore the associations between maternal fasting, neonatal anthropometry, and colostrum cortisol. Eighty-eight percent of participants engaged in some fasting and 57% fasted every day of Ramadan that passed before childbirth. Participants largely expressed family support for their decisions regarding participation in fasting. Women who fasted or fasted more days were lower in weight and higher in body fat. They were less likely to have diabetes, hypertension, or anemia, take vitamins, or receive advice not to fast by doctors or family members. Several variables associated with fasting behaviors also predicted infant anthropometry and colostrum cortisol. Women who engaged in any fasting had infants with lower weight, length, and head circumference for gestational age. The number of days between cessation of fasting and birth was positively associated with neonatal weight, length, and head circumference, possibly suggesting in utero catch up growth. Although increased infant leanness was predicted from other situations of food restriction in late pregnancy, no associations were found between maternal fasting and neonatal ponderal index, arm circumference, or skinfold measurements. Ramadan fasting may be better modeled by situations of stress and dehydration. vi Colostrum cortisol concentration was higher among women who opted out of some or all fasting, possibly indicating underlying differences in metabolic hormones between women who find fasting more difficult versus less. Fasting duration was positively correlated with colostrum cortisol, supporting the hypothesis that maternal fasting contributes to variation in colostrum composition. This research elucidates some reproductive health consequences related to the religious fasting associated with Ramadan. The findings of this research contribute to the literature on fetal and lactational programming and our understanding of how the intrauterine and postnatal environments are shaped by the interplay between biology and culture in the maternal environment.