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 (β = .29) and BP (β = .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.