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

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).

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).

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).

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.