Maternal pre-pregnancy BMI, gestational weight gain and breastfeeding

The aims were to investigate the association of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) with breastfeeding (BF) duration and BF pattern at 3 months of age.

This was a prospective cohort study of 4231 children who were enrolled at birth and were followed-up at 3, 12, 24 and 48 months of age to gather information on maternal and offspring characteristics including BF patterns and BF duration. Maternal pre-pregnancy BMI was categorized according to the WHO classification and GWG according to the 2009 Institute of Medicine recommendations. Cox's proportional hazards model was used to assess whether pre-pregnancy BMI and GWG were associated with BF and exclusive breastfeeding (EBF) duration. Predicted probabilities of BF patterns at 3 months were estimated by multinomial logistic regression.

Information on BF was available to 4011 infants. The total BF and EBF median durations were 7.0 months and 1.5 months, respectively. There were no differences in duration of any BF or EBF according to pre-pregnancy BMI or GWG categories. There was an increased predicted probability for weaning before the age of 3 months among infants from obese women, compared with those from mothers with normal pre-pregnancy BMI, with margins adjusted predictions of 0.36 (95% confidence interval (CI) 0.31-0.41) and 0.23 (95% CI 0.21-0.25), respectively.

Infants from pre-pregnancy overweight/obese mothers presented higher probability of early weaning compared with infants from normal-weight mothers. Obese/overweight pregnant women need supplementary guidance about BF benefits to infant health during prenatal and postnatal care.