Early Second Trimester Weight Gain in Obese Women Predicts Excessive Gestational Weight Gain in Pregnancy

To assess gestational weight gain (GWG) in obese women to determine an inflection point that identifies women at risk for excessive weight gain.

This is an observational prospective cohort study of pregnancies managed through the UC San Diego Maternal Weight and Wellness Program from 2011 to 2014. The primary outcome was total gestational weight gain. GWG was categorized as inadequate (<11 pounds), adequate (11–20 pounds), and excessive (>20 pounds) based on Institute of Medicine (IOM) recommendations. Other outcomes were GWG by trimester and postpartum weight retention. Bivariate and multivariate analyses were used to assess factors associated with GWG.

Ninety-five patients had a mean prepregnancy body mass index (BMI) of 41.9 ± 8.9 kg/m² and a net weight gain of 21.9 ± 19 pounds. First trimester GWG was −0.3 ± 4.9 pounds, second trimester was 10.4 ± 10.8 pounds, and third trimester was 11.4 ± 8.5 pounds for all participants. Women who exceeded IOM recommendations accelerated weight gain at 12–14 weeks and gained a majority of weight during the second trimester. Weight gain of more than two pounds at 12–14 weeks had a 96 % positive predictive value (95 % CI 79–99) for excessive GWG. Postpartum women with excessive GWG retained more weight than those with inadequate GWG (10.7 ± 15.6 pounds compared with −13.6 ± 10.9 pounds, P < 0.001). On multiple linear regression GWG by trimester was predictive of total GWG with second and third trimester GWG having the greatest effect on total GWG. Prepregnancy BMI and gestational diabetes were not predictors of total GWG.

Obese women at risk for excessive GWG may be identified as early as 12–14 weeks and gain most weight during the second trimester. GWG less than 11 pounds resulted in significant postpartum weight loss among obese women.