Perinatal outcomes among women with bipolar disorder: a population-based cohort study

OBJECTIVE: To evaluate the risk of adverse perinatal outcomes among pregnant women previously hospitalized for bipolar disorder. STUDY DESIGN: We completed a population-based cohort study of women with a singleton delivery in Ontario, Canada (2003 to 2011). Women previously hospitalized for bipolar disorder (n = 1859) or major depressive disorder (n = 3724) were each compared to women without a documented mental illness (n = 432,358). Main study outcomes were preterm birth, severe small for gestational age < 3rd percentile birthweight, and severe large for gestational age > 97th percentile birthweight. Secondary outcomes included stillbirth, congenital malformations, neonatal morbidity and readmission to hospital < 28 days. Odds ratios (ORs) were adjusted for maternal age, parity, prepregnancy obesity, substance use, and diabetes mellitus or hypertension before or during pregnancy. RESULTS: Bipolar disorder (adjusted OR [AOR], 1.95; 95% confidence interval [CI], 1.68-2.26) and major depressive disorder (AOR, 1.91; 95% CI, 1.72-2.13) were each associated with preterm birth. Bipolar disorder was associated with severe large for gestational age (AOR, 1.31; 95% CI, 1.03-1.67). Major depressive disorder was associated with severe small for gestational age (AOR, 1.22; 95% CI, 1.05-1.42). Both mood disorder groups had significantly higher risk of congenital malformations, neonatal morbidity, and neonatal hospital readmission. Although study covariates explained some of the increased risk, we could not address all potential explanatory factors. CONCLUSION: Women previously hospitalized for bipolar disorder are at increased risk of adverse perinatal outcomes compared with the general population. Their level of risk is comparable to women previously hospitalized for major depressive disorder. These risks must be considered in the management of pregnant women with a history of major mood disorders. Attention to potentially modifiable risk factors such as obesity, diabetes, and hypertension before and during pregnancy could reduce the risk for adverse perinatal outcomes.