Prepregnancy Body Mass Index Shift Across Gestation: An Association with Breastfeeding Practices?

Background: Research has shown that mother's obesity and underweight are major risk factors for reduced initiation, duration, and exclusivity of breastfeeding.

Objective: We compared breastfeeding practices from discharge until the third postnatal month in women, accounting to prepregnancy body mass index (BMI) and its shift across gestation.

Study Design: Data on maternal shifts in BMI category from prepregnancy to gestational BMI by gestational weight gain (GWG) were defined according to 2009 Institute of Medicine (IOM) guidelines. Logistic regression models were estimated to assess the effect of prepregnancy and gestational BMI on breastfeeding, adjusting for clinically relevant factors.

Results: The analysis included 658 women. According to prepregnancy BMI, 84 (12.8%) mothers were underweight, 444 (67.4%) were normal weight, 94 (14.3%) were overweight, and 36 (5.5%) were obese. Although in the range defined by IOM 2009, GWG shifted across the BMI categories in 445 (67.6%). Thus, while underweight women shifted in higher BMI categories, normal weight women category halved (230, 35%), and both overweight women (301, 45.7%) and obese women (127, 19.3%) tripled. Breastfeeding patterns at discharge, at first month, and at third month were comparable among prepregnancy and gestational BMI groups, except for prepregnancy BMI groups at third month (p 0.03). At multivariable analysis, neither prepregnancy BMI nor gestational BMI was associated with reduced exclusive breastfeeding within 3 months after discharge.

Conclusions: Prepregnancy BMI and gestational BMI, in women with adequate GWG, do not affect exclusive breastfeeding initiation, duration, and exclusivity until the third month postpartum. Women need information and support to gain adequate weight during pregnancy.