Obesity and adverse pregnancy outcomes in twin pregnancies

Objective: To compare pregnancy outcomes in twin pregnancies based on maternal pre-pregnancy body mass index (BMI). Methods: Historical cohort study of all twin pregnancies >24 weeks managed by one maternal-fetal medicine practice from 2005 to 2012. We compared pregnancy outcomes between pre-pregnancy obese (BMI >= 30kg/m(2)) and normal weight women (BMI 18.5-24.99 kg/m(2)). We also compared pre-pregnancy normal weight women to overweight women (BMI 25-29.99 kg/m(2)) and underweight women (BMI <18.5 kg/m(2)). Chi square, Fisher's exact test, Student's t-test, and one-way ANOVA were used as appropriate. A p value of <0.05 was considered significant. Results: Five hundred fourteen patients with twin pregnancies were included. Pre-pregnancy obesity was associated with gestational hypertension (34.1% versus 17.9%, p=.011), preeclampsia (27.3% versus 14.4%, p=.028), and gestational diabetes (22.2% versus 4.7%, p<.001). Pre-pregnancy overweight was associated with gestational diabetes (13.7% versus 4.7%, p=.002). Pre-pregnancy underweight was not associated with any adverse pregnancy outcomes. Comparing outcomes across normal weight, overweight, and obese women, the rates of gestational diabetes and gestational hypertension increased significantly across the three groups. Conclusion: In patients with twin pregnancy, pre-pregnancy obesity is associated with adverse pregnancy outcomes, including gestational diabetes, gestational hypertension, and preeclampsia.