(PTFS09-02-26) Direct and Circulating Adipokine–Mediated Effects of Maternal BMI and Diet Quality on Human Milk Adipokines

Objectives: We evaluated associations between maternal body mass index (BMI) and diet quality with milk adiponectin (ADP) and leptin (LEP) levels and whether circulating adipokines explains these associations.

Methods: Mothers (n = 78) from the MOM2CHild cohort were included. Maternal BMI was derived from weight measured at week 2 postpartum and self-reported height, serving as a proxy for late pregnancy adiposity. Maternal diet quality was assessed using the Healthy Eating Index 2015 (HEI) based on Diet History Questionnaire-III data collected at third trimester of pregnancy. Higher HEI indicates better diet quality. ADP and LEP were assayed in third trimester serum and week 2 postpartum milk by validated high-sensitivity ELISA kits. We performed mediation analysis using natural log-transformed adipokine levels to assess whether circulating adipokines mediates associations of maternal BMI and HEI with milk adipokines (adjusted for confounders) using R mediation package with 1000 bootstrap.

Results: Mean ± SD for maternal age, BMI, and HEI were 33.1 ± 4.1 years, 29.1 ± 6.2 kg/m2, and 62.2 ± 9.9, respectively. Average of log-transformed (ng/mL) ADP and LEP levels were 9.4 ± 0.5 and 3.6 ± 0.7 in serum; and 2.8 ± 0.4 and -0.7 ± 0.9 in milk, respectively. Maternal BMI was inversely associated with ADP in serum (β ± SE: -0.02 + 0.01, p = 0.016) and milk (total effect: - 0.03 ± 0.007). Serum ADP explained 22% of the effect of BMI on milk ADP (indirect: -0.006 ± 0.003, p = 0.01; direct: -0.02 ± 0.007, p = 0.004). HEI was not associated with serum ADP, but was positively associated with milk ADP (total effect: 0.01 ± 0.04) and it was not explained by serum ADP. Maternal BMI was positively associated with LEP in serum (β ± SE: 0.07 ± 0.01, p < 0.0001) and milk (total effect: 0.1 ± 0.01, p < 0.0001). Half of the association of BMI with milk LEP was explained by serum LEP (indirect: 0.05 ± 0.01, p < 0.0001; direct: 0.05 ± 0.02, p < 0.01). HEI was not associated with serum or milk LEP.

Conclusions: Effects of BMI on milk ADP and LEP were partially explained by circulating levels, with a greater indirect effect on LEP. However, positive association of diet quality with milk ADP was not explained by serum levels. A greater understanding of the transport of these adipokines in milk and their local synthesis in mammary gland are needed.

Funding Sources: NICHD, NIAID