Influence of maternal excess weight before pregnancy on breast-feeding and weaning: pooled analyses of four population-based cohorts born between 1982 and 2015.

Purpose To investigate the associations of maternal excess weight before pregnancy with (1) weaning at age 3mo, (2) duration of exclusive breastfeeding at age 6mo, (3) duration of any breastfeeding at age 12mo; and (4) to compare the magnitude of these associations over four decades. Methods Data were from participants in the Pelotas (Brazil) Birth Cohorts born in 1982 (N=5,334), 1993 (N=1,442), 2004 (N=4,092) and 2015 (N=4,102). Maternal pre-pregnancy weight was collected after the delivery and breastfeeding status was assessed when children were three and 12 months old. Results Only in the most recent cohort (2015), women with excess weight [body mass index (BMI) ≥ 25 kg/m2) before pregnancy had higher risk of discontinuing exclusive breastfeeding within the first six months post-partum than women with normal weight [HR= 1.22 (95%CI 1.15; 1.30)]. Duration of any type of breastfeeding until 12 months of age was not affected by pre-pregnancy weight. Conclusion Excess weight before pregnancy is associated with exclusive breastfeeding only in the most recent birth cohort coinciding with increases in weight excess and breastfeeding over time.