Maternal prepregnant body mass index, duration of breastfeeding, and timing of complementary food introduction are associated with infant weight gain

Background: Women who are overweight or obese before pregnancy breastfeed for shorter durations than do normal-weight women. These shorter durations may place infants of overweight and obese women at risk of not receiving the benefits of breastfeeding, which may include a reduced risk of overweight later in life. Objective: We examined how maternal prepregnant body mass index (BMI; in kg/m(2)) and infant feeding pattern are associated with infant weight gain. Design: In this prospective, observational study, we used multiple regression analyses adjusted for potential confounding factors to examine these associations among 3768 mother-infant dyads from the Danish National Birth Cohort. Results: In multiple regression analyses, increasing maternal prepregnant BMI, decreasing durations of breastfeeding, and earlier complementary food introduction were associated with increased infant weight gain. An interaction was identified for short durations of breastfeeding (<20 wk). Earlier complementary food introduction (<16 wk) was associated with greater infant weight gain; however, the timing of complementary food introduction did not increase infant weight gain at longer durations of breastfeeding (greater than or equal to20 wk). In this sample. prepregnant obesity (BMI greater than or equal to 30.0), short durations of breastfeeding, and earlier introduction of complementary food were associated with 0.7 kg of additional weight gain during infancy. Conclusions: Infant weight gain is associated with maternal prepregnant BMI and with an interaction between the duration of breastfeeding and the timing of complementary food introduction. Future investigations of the effects of breastfeeding on infant weight gain should account for all of these factors.