Preterm human milk composition in conditions of maternal overweight and obesity and effects of milk constituents on preterm infant body composition

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Considering the increasing rates of maternal overweight and obesity (OW/OB) in pregnancy and lactation, a knowledge gap exists regarding influences of the maternal metabolism on preterm infant health through alterations in preterm human milk composition. There is a critical need to define longitudinal changes in preterm milk composition resulting from maternal OW/OB especially in conjunction with preterm infant health outcomes. Our long-term goal is to optimize knowledge of human milk nutrient quality in conditions of preterm birth while ac- counting for the changing epidemiology of maternal health in pregnancy and lactation. The overall objective is to document longitudinal changes in preterm human milk composition, specifically milk fatty acids (FA) and hormones, associated with maternal OW/OB and measure regulatory effects of milk components on infant body composition. Our central hypothesis is that women with OW/OB produce preterm milk that is compositionally different from women with normal weight and that preterm infant adiposity is susceptible to maternal metabolic status and diet via altered milk composition. The rationale for this proposed research is to advance and tailor recommendations for preterm infant nutrition, assuring guidelines account for infant and maternal metabolism. To fulfill these objectives and test the hypotheses, Aim 1 will document longitudinal changes in preterm milk FA and hormones associated with regulation of infant body composition, measuring variability resulting from maternal OW/OB. This will be accomplished in a prospective cohort study of mother-preterm infant dyads with two groups enrolled (n=144 total participants): 1. Primary: women who deliver at 280/7-316/7 weeks of gestation and their infants (n=42 women, n=42 infants) and 2. Reference: comparison women who deliver at 340/7-366/7 weeks of gestation and their infants (n=30 women, n=30 infants). Screening and enrollment will ac- count for pre-pregnancy body mass index (BMI) to accrue an even distribution across normal, overweight and obese BMIs (one-third in each) for both groups. Serial preterm milk samples will be obtained through week 5 of lactation. Rigorous clinical phenotyping of women and infants will occur as well as obtaining women’s dietary intake during lactation. Aim 2 will assess the association of milk FA and hormone intake with preterm infant body composition. Air displacement plethysmography as well as skin folds thickness will measure infant body composition. Infant intake of milk FA and hormones will be estimated by documenting daily nutritional intake and then evaluated in relation to infant body composition. The proposed contributions are significant because they will identify aspects of both maternal and preterm infant nutrition that are amenable to intervention and which hold greatest potential to address human milk variability and the metabolic susceptibilities of the preterm infant not as yet incorporated within infant feeding standards. The planned research is innovative in proposing to advance the science towards defining preterm infant nutritional status and requirements using enhanced risk stratification, based in part on indicators of maternal metabolism and health during pregnancy and lactation.