Association between maternal prepregnancy obesity and breastfeeding duration: Data from a nationwide prospective birth cohort.

Association of maternal obesity with shorter breastfeeding duration may involve different factors and might be modified by parity. In a national birth cohort, we aimed to estimate the association between prepregnancy body mass index (pBMI) and breastfeeding duration after adjustment for sociodemographic, pregnancy, and other characteristics and assess the effect modification of parity in such associations. In 2012, 3,368 mother-infant dyads were randomly included at birth in the French Epifane cohort. Breastfeeding information was collected in maternity wards and by phone interview at 1, 4, 8, and 12 months postpartum. Poisson regression analyses estimated the association of pBMI with the number of days of "any breastfeeding" (ABF) and "exclusive breastfeeding" (EBF) in unadjusted and adjusted models. Interactions between parity and pBMI were tested. Obesity before pregnancy was independently associated with shorter ABF duration (incidence rate ratio [IRR] = 0.86, 95%CI [0.74, 0.99]) compared to normal-weight status. Parity showed an effect modification only with EBF duration. Among primiparae, no association was found for obesity, but overweight was significantly associated with shorter EBF duration independently of all covariates (IRR = 0.74 [0.58, 0.95]). Among multiparas, obesity was associated with shorter EBF duration after controlling for sociodemographic factors (IRR = 0.71 [0.53, 0.95]). This association was no longer statistically significant after controlling for other covariates. Obesity appears to be a strong risk factor in shorter ABF duration. Furthermore, parity is a key factor in the relationship of pBMI to shorter EBF duration. Overweight primiparous and obese multiparous women need additional support to prolong breastfeeding duration.