Masako Fujita

MASAKO FUJITA, Michigan State University, East Lansing, Michigan, was awarded a grant in April 2016 to aid research on ‘The Impact of Maternal Nutrition and Infant Sex on Breast Milk Quality in Polygynous Ariaal Agro-pastoralists of Northern Kenya.’ Inequalities in child mortality between the poorest and richest households and between boys and girls are persistent where undernutrition and gender discrimination are common. This may be because of the different levels of protection children receive from mothers’ milk that may vary with maternal nutrition and infant sex. To evaluate this possibility, the study applied the Trivers-Willard hypothesis (TWH). TWH predicts unequal parental investment between daughters and sons in polygynous populations where the marriageability of males is dictated by their health/wealth while marriageability of females is less variable. Specifically, TWH predicts that mothers in good condition will invest more in sons while mothers in poor condition will invest more in daughters because these strategies may enhance their reproductive success under the system of polygyny. Two milk components known to facilitate infant health ‘ folate-binding protein (FOLR1) and secretory immunoglobulin A antibody (sIgA) ‘ were examined as an indicator of maternal investment using archived breast milk samples from a polygynous population in Kenya. Results: maternal undernutrition (low arm fat) co-occurred with low sIgA. Furthermore, the milk of under-nourished mothers exhibited preference toward daughters. Maternal undernutrition may compromise immune protection for infants, particularly for male infants, and may contribute to inequalities in child mortality.