How do pregnancy-related weight changes and breastfeeding relate to maternal weight and BMI-adjusted waist circumference 7 y after delivery? Results from a path analysis

Background: Reproduction has been related to long-term maternal weight gain, and changes in fat mass, with gestational weight gain, have been identified as an important contributor. However, the influence of weight changes during the whole reproductive cycle and the modifying effect of breastfeeding are unknown. Objective: The objective was to examine how prepregnancy weight, gestational weight gain, postpartum weight changes, and breastfeeding influence maternal weight and body mass index–adjusted waist circumference (WC(BMI)) 7 y after delivery. Design: This was a prospective cohort study of 23,701 women participating in the Danish National Birth Cohort with singleton births and no births during follow-up. Path analysis was used to assess the total, direct, and indirect effects; the latter was mediated through weight changes on the pathways. Results: Postpartum weight retention at 6 mo and weight gain from 6 to 18 mo postpartum were highly positively associated with both outcomes. A 1-kg increase in weight retention at 6 mo postpartum corresponded to an average increase of 0.5 kg at 7 y. Gestational weight gain was not associated with WC(BMI) but was positively associated with weight at 7 y; 87% of this effect was mediated through later weight changes. For both outcomes, a small inverse association was observed for breastfeeding duration. This was strongest for WC(BMI), for which 97% of the effect was direct, ie, not mediated through postpartum weight. Conclusions: These findings show that postpartum weight retention at 6 mo and weight gain from 6 to 18 mo postpartum contribute equally to adverse maternal anthropometric measures 7 y after delivery. Breastfeeding duration may have a beneficial effect.