Increasing pre-pregnancy body mass index is predictive of a progressive escalation in adverse pregnancy outcomes

OBJECTIVE: To evaluate the association between pre-pregnancy body mass index (BMI) and adverse pregnancy outcomes using a large administrative database. METHODS: Retrospective cohort study of California women delivering singletons in 2007. The association between pre-pregnancy BMI category and adverse outcomes were evaluated using multivariate logistic regression. RESULTS: Among 436,414 women, increasing BMI was associated with increasing odds of adverse outcomes. Obese women (BMI=30-39.9) were nearly 3 x more likely to have gestational diabetes (OR=2.83, 95% CI=2.74-2.92) and gestational hypertension/preeclampsia (2.68, 2.59-2.77) and nearly twice as likely to undergo cesarean (1.82, 1.78-1.87), when compared to normal BMI women (BMI=18.5-24.9). Morbidly obese women (BMI ≥ 40) were 4x more likely to have gestational diabetes (4.72, 4.46-4.99) and gestational hypertension/preeclampsia (4.22, 3.97-4.49) and nearly 3 x as likely to undergo cesarean (2.60, 2.46-2.74). CONCLUSION: There is a strong association between increasing maternal BMI and adverse pregnancy outcomes. This information is important for counseling women regarding the risks of obesity in pregnancy.