Breastfeeding and maternal weight changes during 24 months post-partum: a cohort study.

The relationship between breastfeeding and the loss of weight gained during pregnancy remains unclear. This study aimed to investigate the association between breastfeeding and maternal weight changes during 24 months post-partum. We studied a dynamic cohort comprising 315 women living in two cities in the state of Bahia, Brazil. The outcome variable was change in the post-partum weight; the exposure variable was the duration and intensity of breastfeeding. Demographic, socio-economic, environmental, reproductive and lifestyle factors were integrated in the analysis as covariates. The data were analysed using multiple linear regression and linear mixed-effects models. The average cumulative weight loss at 6 months post-partum was 2.561 kg (SD 4.585), increasing at 12 months (3.066 kg; SD 5.098) and decreasing at 18 months (1.993 kg; SD 5.340), being 1.353 kg (SD, 5.574) at 24 months post-partum. After adjustment, the data indicated that for every 1-point increase in breastfeeding score, the estimated average post-partum weight loss observed was 0.191 kg at 6 months (P = 0.03), 0.090 kg at 12 months (P = 0.043), 0.123 kg at 18 months (P < 0.001) and 0.077 kg at 24 months (P = 0.001). Based on these results, we concluded that despite the low expressiveness, the intensity and duration of breastfeeding was associated with post-partum weight loss at all stages of the study during the 24-month follow-up.