Impact of overweight and obesity on pregnancy outcomes in women with gestational diabetes – results from a retrospective multicenter study

OBJECTIVE: The aim of this study was to evaluate the impact of pre-pregnancy body mass index (BMI) on pregnancy outcomes in women with gestational diabetes (GD). SUBJECTS AND METHODS: Retrospective multicenter study using data from the Portuguese National Register. We included women with GD with a singleton pregnancy. GD diagnosis was according to the International Association of the Diabetes and Pregnancy Study Group criteria. Women were divided into groups according to their pre-pregnancy BMI: < 18.5 kg/m(2) (underweight), ≥ 18.5 and < 25.0 kg/m(2) (normal weight), ≥ 25 and < 30 kg/m(2) (overweight) and ≥ 30 kg/m(2) (obese). RESULTS: We included 3,103 pregnant women with GD, 29.6% (n = 918) were overweight and 27.3% (n = 846) were obese. Compared to normal weight, the overweight and obese groups had a higher percentage of gestational hypertension (4.0% and 8.5% vs. 2.1%), cesarean delivery (32.8% and 41.3% vs. 27.9%), macrosomia (3.9% and 6.7% vs. 2.4%), and large for gestational age (LGA) newborns (8.3% and 13.5% vs. 6.0%). Obesity increased the risk of gestational hypertension (OR 4.5, p < 0.001), preeclampsia (OR 1.9, p = 0.034), cesarean delivery (OR 2.0, p < 0.001), macrosomia (OR 3.1, p < 0.001) and LGA (OR 2.3, p < 0.001). CONCLUSION: In pregnant women with GD, pregnancy complications increase with pre-pregnancy BMI. In obese women, appropriate diet and counseling prior to gestation and more aggressive medical intervention during pregnancy are needed in order to prevent macrosomic and LGA newborns and to reduce maternal complications.