Antenatal body mass index (BMI) and weight gain in pregnancy - its association with pregnancy and birthing complications

Background: Overweight and obesity is a serious health risk in both developed and developing nations. It is a common finding among women in their reproductive age. Half of patients entering their pregnancy in the US have a BMI >25.0 and therefore qualify as overweight or obese. Moreover, there is a tendency towards increased weight gain during pregnancy. Studies have shown that gestational overweight is associated with complications in pregnancy and birthing as well as short-term and long-term impacts on neonatal outcome in childhood and adulthood. Methods: Five hundred and ninety-one women visiting our tertiary perinatal center in 2014 were analyzed for antenatal BMI, gestational weight gain, as well as pregnancy outcome and complication together with neonatal weight and outcome. Pregnancy weight gain was assessed based on the IOM guidelines (Institute of Medicine) issued in 2009. Results: Twenty-nine percent of our population was overweight with a BMI of more than 25.0. The general weight gain was in every BMI group similar (median ranging from 12.0 to 14.0 kg). Approximately one third gained more than the appropriate amount (37%, P<0.001). Women with more gestational weight were at risk of labor induction (55.0% vs. 45.7% labor induction in total, P=0.007). Strikingly, those patients were found to have significantly higher rates of secondary cesarean section (22.4% vs. 15.4%) and decreased chances of spontaneous vaginal birth (57.5% vs. 61.4%) (P=0.008). Furthermore women with a pregnancy weight gain in excess of the guidelines gave birth to neonates with a higher birth weight (>75. centile, 28.3% vs. 21.3%, P<0.001). Conclusions: Altogether, one third of the analyzed population is already overweight or obese when entering pregnancy. A higher gestational weight gain than the recommended amount was found in 37% of cases. We found an association with pregnancy and birthing complications as well as higher infant weight. This highlights the importance of preconceptive and prenatal advice, and if necessary, intervention on BMI and weight gain.