Independent and Joint Associations of Age, Pre-pregnancy BMI, and Gestational Weight Gain with Adverse Pregnancy Outcomes in Gestational Diabetes Mellitus

Abstract

Introduction: To explore the independent and combined effects of maternal age, pre-pregnancy body mass index (BMI), and gestational weight gain (GWG) on pregnancy outcomes in gestational diabetes mellitus (GDM). Methods: A total of 2171 pregnant women with GDM attending the Women's Hospital of Zhejiang University were retrospectively included. We compared pregnancy outcomes in different age, BMI, and GWG groups after adjusting for confounding variables. Results: Results showed that (1) advanced maternal age increased the risk of primary Cesarean section and hypertensive disorders of pregnancy (HDP) in normal weight; (2) independent of age and GWG, high BMI significantly increased the risk of HDP, primary Cesarean section, and macrosomia; (3) Women with excessive GWG had a higher risk of primary Cesarean section and HDP, even they were ≤ 29 years old or normal weight, respectively; (4) Pregnant women with inadequate GWG had a higher risk of preterm birth and a lower risk of macrosomia in both the 30–34 age group and the normal weight group; (5) BMI was a better predictor of HDP than GWG among women younger than 30. Conclusions: Among the GDM population, women over the age of 35, overweight and obese, or with an excessive GWG were more prone to adverse pregnancy outcomes, especially primary Cesarean delivery and HDP.