Associations of Maternal Weight Status Before, During, and After Pregnancy with Inflammatory Markers in Breast Milk

OBJECTIVE: To examine the associations of maternal weight status before, during, and after pregnancy with breast milk C-Reactive Protein (CRP) and Interleukin-6 (IL-6), two bioactive markers of inflammation, measured at one and three months postpartum. METHODS: Participants were 134 exclusively breastfeeding mother-infant dyads taking part in the Mothers and Infants LinKed for Health (MILK) study, who provided breast milk samples. Pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) were assessed by chart abstraction; postpartum weight loss was measured at the one and three month study visits. Linear regression was used to examine the associations of maternal weight status with repeated measures of breast milk CRP and IL-6 at one and three months, after adjustment for potential confounders. RESULTS: Pre-pregnancy BMI and excessive GWG, but not total GWG or postpartum weight loss, were independently associated with breast milk CRP after adjustment (β=0.49, p<0.001 and β=0.51, p=0.011, respectively). No associations were observed for IL-6. CONCLUSIONS: High pre-pregnancy BMI and excessive GWG are associated with elevated levels of breast milk CRP. The consequences of infants receiving varying concentrations of breast milk inflammatory markers are unknown; however, we speculate that there are implications for the intergenerational transmission of disease risk.