Excessive gestational weight gain is an independent risk factor for gestational diabetes mellitus in singleton pregnancies: Results from a French cohort study

•This study evaluates the impact of maternal obesity and excessive GWG on pregnancy.•Maternal obesity and excessive GWG are associated with gestational diabetes, C-section and macrosomia.•This study confirms that excessive GWG is an independent risk factor for gestational diabetes. Increase in prevalence of maternal obesity worldwide raises concern among health professionals. Our purpose was to evaluate the impact of maternal obesity and of excessive gestational weight gain (GWG) on the course of singleton pregnancies in a French maternity ward. 3599 consecutive women who delivered from April 2013 to May 2015 at Brest University Hospital were included in HPP-IPF cohort study, a study designed to evaluate clinical and biological determinants of postpartum hemorrhage (PPH). Maternal obesity was defined by a pre-pregnancy Body Mass Index (BMI) ≥ 30 kg/m2 and excessive GWG was defined according to the Institute of Medicine 2009 guidelines. Obstetric complications(including gestational diabetes mellitus (GDM), gestational hypertension, pre-eclampsia, venous thromboembolism, PPH, cesarean section (C-section) and macrosomia) were collected prospectively in a standardized case report form. For each complication, Odd Ratios (OR) according to pre-pregnancy BMI and GWG were calculated in univariable and multivariable analyses. Out of the 3162 women analyzed for this report, 583 (18.4%) were overweight, 400 (12.7%) were obese and 36.6% had excessive GWG. In multivariable analysis, after adjustment for confounding factors, obese women were at increased risk of GDM (OR 5.83, 95%CI 4.37–7.79), PPH (OR 1.69, 95%CI 1.19–2.41), C-section (OR 2.50, 95%CI 1.92–3.26) and macrosomia (OR 1.90, 95%CI 1.31–2.76). Similarly, women with excessive GWG were at increased risk of GDM (OR 1.55, 95%CI 1.17–2.06), C-section (OR 1.46, 95%CI 1.16–1.83) and macrosomia (OR 2.09, 95%CI 1.50–2.91). Maternal obesity and excessive GWG are independent risk factors for GDM, C-section and macrosomia in singleton pregnancies. Further studies are needed to evaluate if a lifestyle intervention aiming at avoiding excessive GWG could improve clinical outcomes in pregnant women.