Maternal pre-pregnancy body mass index, gestational weight gain influence birth weight

Evidence suggests that pre-pregnancy body mass index and gestational weight gain have impact on pregnancy and birth weight, yet whether maternal gestational weight gain has a differential effect on the rates of adverse birth weight among women with different pre-pregnancy body mass index categories are unknown.

We selected 1617 children matched with their mothers as study subjects. The subjects were divided into three categories: weight gain below the American Institute of Medicine guidelines, weight gain within the American Institute of Medicine guidelines and weight gain above the American Institute of Medicine guidelines.

The prevalence of pre-pregnancy underweight and overweight/obese women was 16.3% and 12.3%. And nearly 15.2% of the women had gestational weight gain below American Institute of Medicine guideline, 52.1% of the women had gestational weight gain above American Institute of Medicine guideline. Maternal overweight and obese was associated with increased risk for macrosomia and large-for-gestational age. Women had gestational weight gain below American Institute of Medicine guideline were more likely to have low birth weight and small-for-gestational age than women who had gestational weight gain within American Institute of Medicine guideline. Furthermore, the risks for macrosomia and large-for-gestational age were increased in women with above American Institute of Medicine guideline. And for women with a normal weight before pregnancy, gestational weight gain above the American Institute of Medicine guidelines were associated with higher rates of macrosomia and large-for-gestational age, compared with the women of similar pre-pregnancy weight category but with gestational weight gain within the American Institute of Medicine guidelines.

Women with abnormal pre-pregnancy body mass index and gestational weight gain are at risk for adverse birth weight outcomes. Moreover, gestational weight gain has a differential effect on the rates of adverse birth weight outcomes between women of different pre-pregnancy body mass index categories.