Objective: The goal of this study was 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 1 and 3 months post partum. 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 1- and 3-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 1 and 3 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, it is speculated that there are implications for the intergenerational transmission of disease risk.
Bibliographical noteFunding Information:
Funding agencies: This work was supported by R01HD080444 from the National Institute of Child Health and Human Development (NICHD). KMW was supported by training grant T32HL007779. Disclosure: The authors declared no conflict of interest. Author contributions: DAF and EWD conceived the project and were responsible for data collection. KMW ran the statistical analyses and wrote the manuscript. LF and KDS assisted with data collection. AMT conducted all breast milk assays. JLH was responsible for data management. DRJ and EWD assisted with statistical analyses. RCM completed the literature review. All authors critically reviewed the manuscript and had final approval of the submitted and published versions. Received: 22 June 2017; Accepted: 18 August 2017; Published online 6 October 2017. doi:10.1002/oby.22025