Maternal blood pressure mediates the association between maternal obesity and infant weight gain in early postpartum

Background It is unknown to what extent higher maternal blood pressure (BP) in early postpartum impacts the relationship between higher maternal weight status and greater infant weight gain in early postpartum. Objective To evaluate the mediating role of higher maternal BP at 1 month postpartum on the association between higher maternal weight status at 1 month postpartum and greater infant weight gain over 6 months postpartum. Methods Participants were 169 Hispanic mother-infant pairs. Maternal body mass index (BMI) and BP were assessed at 1 month postpartum. Infant weight was measured at 1 and 6 months postpartum to calculate weight-for-age z scores (WAZ). Multiple linear regression models were used for prediction, and Sobel test was used to determine mediation. Results Controlling for maternal pre-pregnancy BMI, age, delivery mode, infant sex, and infant birth weight revealed that both maternal BMI (beta = .29) and BP (beta = .32) predicted infant WAZ gain (both P <= .03). However, the relationship between infant WAZ gain and maternal BMI was no longer significant after further adjustment for maternal BP, which remained significant (P < .05). Maternal BP explained 23.6% (Sobel T = 2.01) of the association between maternal BMI at 1 month and infant WAZ gain over 6 months. Conclusion Our data suggest that higher maternal weight status at 1 month postpartum is related to greater infant weight gain over 6 months postpartum, and this relationship is mediated by higher maternal BP at 1 month postpartum.