Purpose: The aim of this study was to investigate the association between pre-pregnancy body mass index (BMI) and gestational diabetes mellitus (GDM).
Methods: This prospective study was conducted on 256 pregnant women without diabetes referred for prenatal care in the first trimester of pregnancy to two referral University Hospitals (Shariati and Arash Hospitals) during the years 2012 and 2013. Eligible participants were selected consecutively and were followed until delivery and 6 weeks after that. Body weight and fasting plasma glucose were measured in each trimester, and BMI was calculated. Incidence of GDM was recorded, and BMI in this group was compared with those without GDM.
Results: Mean age of women was 28.70 ± 5.57 years and among them, 78 women (30.5 %) developed GDM of which 21 were obese (52.5 %), 25 overweight (27.8 %), and 32 (25.4 %) were normal weight (p = 0.004). Pre-pregnancy obesity (OR 2.74, 95 % CI 1.28-5.88, p = 0.009), family history of diabetes (OR 2.01, 95 % CI 1.13-3.56, p = 0.016), and maternal age more than 30 years (OR 2.20, 95 % CI 1.25-3.88, p = 0.006) were three independent predictors for GDM, and pre-pregnancy obesity was the most potent predictor of GDM.
Conclusion: Women with high BMI and obesity have a significantly higher risk for developing GDM. Pre-pregnancy obesity, family history of diabetes, and age more than 30 years are three independent risk factors for GDM.
Keywords: BMI; Gestational diabetes mellitus; Obesity.