Gestational weight gain in obese pregnancy: impact on maternal and foetal metabolic parameters and birthweight.

The aim of this prospective, observational study was to investigate the impact of gestational weight gain (GWG) among euglycaemic obese pregnant women on maternal and foetal metabolic parameters and neonatal outcome. Total GWG was recorded for 101 obese, non-diabetic women with a singleton pregnancy. At 28 weeks of gestation, fasting maternal blood samples were analysed for glucose, insulin, c-peptide and lipids. Cord bloods were collected at delivery for analysis of glucose, c-peptide and lipids. GWG (mean ± SD =10.9 ± 5.5 kg) was greatest among those of younger age and lower body mass index and 58% of women exceeded the Institute of Medicine GWG recommendations of 5-9 kg for obese pregnancy. GWG was significantly positively associated with increased risk of birthweight >4 kg, cord c-peptide levels and inversely associated with cord total cholesterol. This study identified that higher GWG in obese pregnancy may increase the risk of macrosomia and neonatal hyperinsulinaemia, within a euglycaemic maternal cohort. Impact statement Excess gestational weight gain (GWG) and maternal obesity frequently co-occur with adverse consequences for maternal and neonatal health; however, little is known of the underlying biological pathways which may be affected to contribute to adverse outcomes. Greater understanding of the biological mechanisms involved may help guide future studies to develop targeted interventions for more effective clinical outcomes. This study identified that higher GWG among obese pregnant women resulted in foetal hyperinsulinaemia even in the absence of maternal hyperglycaemia, potentially representing a biological pathway for larger birthweight babies. These results may highlight the need for more intensive dietary and lifestyle interventions among obese women who would not normally receive additional counselling beyond standard antenatal care if not diagnosed with glucose intolerance in pregnancy.