Gestational weight gain as an independent risk factor for adverse pregnancy outcomes in women with gestational diabetes

OBJECTIVE: Obesity and gestational diabetes mellitus (GDM) are rising worldwide. This study retrospectively evaluated the role of excessive gestational weight gain (eGWG) in women with GDM and different pre-pregnancy body mass indices (BMIs). PATIENTS AND METHODS: Optimal glycaemic control was defined as achieving glucose target thresholds in more than 80% of measurements. 283 women with GDM were categorized as underweight, normal weight, overweight or obese based on WHO's classification scheme. eGWG was defined as >18.0 kilograms for women who were underweight, >15.8 kilograms for those who were normal weight, >11.3 kilograms for those who were overweight and >9.0 kilograms for those who were obese. For the analysis, women were divided into two groups: normal and excessive GWG. The main outcomes measured were incidences of large/small for gestational age (LGA/SGA), macrosomia, preterm delivery, hypertensive disorders and caesarean sections (CS). RESULTS: Excessive GWG was associated with higher birth weight and percentile (p<0.001), and with a higher prevalence of LGA (p<0.001), macrosomia (p=0.002) and hypertensive disorders (p=0.036). No statistical differences were found for the week of delivery, or prevalence of CS and SGA. The multivariate analysis highlighted both pre-pregnant BMI and eGWG as independent risk factors for LGA and macrosomia. Women with a pre-pregnant BMI of at least 25 and eGWG have a 5.43-fold greater risk of developing LGA (p=0.005). CONCLUSIONS: When combined with an inadequate pre-pregnant BMI, eGWG acts as a "synergic risk factor" for a poor outcome. When obesity or GDM occur, an optimal GWG can guarantee a better pregnancy outcome.