Interpregnancy weight change and adverse maternal outcomes: a retrospective cohort study

Examine associations between interpregnancy body mass index (BMI) change (difference in the pre-pregnancy BMIs of two consecutive pregnancies) and gestational diabetes mellitus (GDM), pre-eclampsia (PE), gestational hypertension (GHtn), primary cesarean delivery, and vaginal birth after cesarean delivery (VBAC). Modified Poisson regression models estimated adjusted associations. Every 1-unit increase in interpregnancy BMI increased risks of GDM (relative risk [RR]: 1.09; 95% confidence interval [CI], 1.07–1.11), PE (RR: 1.06; 95% CI, 1.04–1.09), GHtn (RR: 1.08; 95% CI, 1.06–1.10), and primary cesarean delivery (RR: 1.03; 95% CI, 1.01–1.05) and decreased the risk of a successful VBAC (RR: 0.98; 95% CI: 0.97–0.997) in the second pregnancy. A BMI increase of ≥3 units increased risks of GDM (RR: 1.71, 95% CI, 1.52–1.93), PE (RR: 1.60, 95% CI, 1.33–1.94), GHtn (RR: 1.66, 95% CI, 1.42–1.94), and primary cesarean delivery (RR: 1.29, 95% CI, 1.12–1.49) and decreased the risk of a successful VBAC (RR: 0.89; 95% CI, 0.80–0.99) compared to women with interpregnancy BMI change within −1 and +1 unit. GDM was also increased among women increasing their BMI by ≥2 but