LAUSR

Background Many biological, social and cultural barriers for suboptimal breastfeeding practices have been identified in literature. Among these, excessive pre-pregnancy weight has been identified as a risk factor for not initiating breastfeeding early. Social support, coming from social networks (e.g. a partner, family or friends) or health care providers, has been positively associated with breastfeeding. This study aimed to examine the association between pre-pregnancy excessive weight and breastfeeding within the first hour after birth and if social support modifies this association. Design National population-based study conducted with 21,086 postpartum women from February 1, 2011 to October 31, 2012 in 266 hospitals from all five regions of Brazil. Social support was defined as having a companion at the hospital. Main effects and interactions were tested with multivariable regression analyses. Results Multivariate regression analyses indicated that class I and class II obese women had lower odds of breastfeeding within the first hour when a companion was not present (AOR = 0.59, 95% CI 0.42–0.82 and AOR = 0.59, 95% CI 0.36–0.97, respectively), but there was no association when the companion was present. Among overweight and obese women, the predicted probability of breastfeeding within the first hour was lower for those without a companion. This association was not found among those with normal pre-pregnancy BMI. Conclusions Social support modifies the relationship between pre-gestational BMI and breastfeeding initiation among women who are overweight or obese, specifically it reduces the risk of delayed breastfeeding initiation.