(PTFS09-06-26) Milk Adipokines as Predictors of Maternal Milk Production Rate

Objectives: Previously we reported an inverse association between body mass index (BMI) and milk production rate (MPR) in lactating women. Here, we examine if milk adiponectin (ADP) and leptin (LEP), adipokines in serum known to be positively associated with metabolic health (ADP) and adiposity (LEP), are predictive of MPR overall and when controlling for BMI.

Methods: Analysis is based on 90 mothers from the MOM2Child study who prenatally indicated strong exclusive breastfeeding intent, delivered at term, abstained from elective supplement use, and completed MPR assessment at 2 (n=75) and/or 6 weeks (n=73) postpartum. BMI was calculated from measured weight and reported height at each visit. Milk ADP (high molecular weight) and LEP were assayed with validated high-sensitivity ELISA kits and log-transformed for analysis. MPR (g/h) is defined as hour 2 milk yield after bilateral breast emptying at hours 0, 1, and 2. Repeated measurement bivariate models and models adjusted for maternal age, parity, breast emptying frequency, and then BMI, were fit to assess overall association and whether it differed by timepoint with cluster-robust standard errors. Regression coefficients ([beta [95%CI]) are scaled to represent change in MPR (g/h) when the milk adipokine increases from 25th to 75th percentile.

Results: Interactions of timepoint and adipokine in predicting MPR were not significant (P >0.35) and linearity assumptions were met. Pooled (n=148) mean (SD) BMI and MPR were 28.9 ± 6.4 kg/m² and 45 ± 18 g/h. Pooled median [IQR] milk ADP and LEP were 15.4 [11.7 - 24.1] ng/mL and 436 [211 -805] pg/mL. Milk ADP does not predict MPR in any models. Milk LEP is a strong predictor of MPR (-10.0 [-14.5, -5.4], P < 0.001, with covariates); LEP remains strongly predictive with BMI in the model (-9.3 [-15.3, -3.3], P=0.003), with no direct effect of BMI on MPR (-0.1 [-0.8, 0.6], P=0.783).

Conclusions: MPR declines by 10 g/h as milk LEP increases from the 25^th to 75^th percentile but is not associated with milk ADP. Our results suggest that maternal adiposity influences milk production, and this is better reflected in milk LEP than BMI—as the latter is completely attenuated by the inclusion of LEP. In contrast, milk ADP may fail to reflect metabolic health and/or metabolic health itself is not a predictor of milk production.

Funding Sources: NICHD, NIAID, Open Philanthropy