Maternal Prepregnant Body Mass Index and Gestational Weight Gain Are Associated with Initiation and Duration of Breastfeeding among Norwegian Mothers.

BACKGROUND Pregnancy is associated with weight gain. Moreover, overweight and obese women subsequently have difficulties with breastfeeding. Both of these factors may contribute to the observed relations between reproduction and weight problems. OBJECTIVE In this study we evaluated the combined effects of maternal prepregnancy body mass index (BMI) and gestational weight gain (GWG) on the ability to initiate and sustain breastfeeding in a large, population-based study, the MoBa (Norwegian Mother and Child Cohort Study). METHODS Initiation and maintenance of breastfeeding for 4 and 6 mo postpartum in relation to prepregnancy BMI and GWG were evaluated among 49,669 women with complete information on BMI, GWG, and breastfeeding by using multivariable logistic regression analyses. RESULTS An excess risk of unsuccessful initiation of breastfeeding was observed among all categories of prepregnant overweight and obese women as well as among most GWG categories of prepregnant underweight women. For all of these groups, risks of unsuccessful initiation of breastfeeding were significantly higher with GWG below recommendations. The same patterns were seen among all categories of prepregnant overweight and obese women with respect to risks of inability to sustain full or any breastfeeding for 4 and 6 mo postpartum. However, prepregnant obese women had the highest risk of inability to sustain full or any breastfeeding if they had also experienced GWG above recommendations. The associations between prepregnancy BMI and breastfeeding were modified by Apgar scores and maternal asthma. CONCLUSIONS The results show the importance of encouraging women to start pregnancy with a healthy BMI as well as to have GWG within recommendations for the benefit of successful breastfeeding. The interactions with medical conditions further highlight the complexity of the associations.