Timing and Amount of Gestational Weight Gain in Association with Adverse Birth Outcomes

Most existing research on gestational weight gain and pregnancy outcomes has not accounted for timing of weight gain. The area under the weight gain curve (AUC) provides a single measure that incorporates both timing of weight gain and total amount gained. This study evaluated predictors and outcomes associated with second- and third-trimester weight gain AUC from the second and third trimester using time-to-event analysis to account for the correlation between gestational weight gain and gestational duration.

Our prospective cohort study used data from the LifeCodes study at Brigham and Women's Hospital. Maternal weights were available from all prenatal and study visits. We used log-Poisson models with empirical variance estimation to identify predictors of total AUC from 14 weeks to delivery and Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between AUC quintile and adverse pregnancy outcomes.

Compared to the middle quintile, the highest quintile of accumulated pound-days was associated with a decreased hazard of spontaneous preterm birth among multigravid women (HR = 0.44; 95% CI = 0.23, 0.84), a decreased hazard of small-for-gestational-age births (HR = 0.65; 95% CI = 0.45, 0.92) overall and an increased hazard of large-for-gestational-age births among normal and underweight women (HR = 3.21; 95% CI = 1.50, 6.89) CONCLUSIONS:: In our study, a pattern of gestational weight gain characterized by more rapid gains earlier in pregnancy was associated with improved pregnancy outcomes in some subgroups of pregnant women.