A too-high gestational weight gain, in combination with steadily increasing obesity rates among women of reproductive age, represents an enormous obstetrical problem, as obesity and high gestational weight gain are associated with enhanced fetal growth, low vital parameters, and increased cesarean section rates. This medical record-based study investigates the association patterns between too-low as well as too-high gestational weight gain, according to the 2009 Institute of Medicine (IOM) guidelines, and fetal growth, as well as birth mode and pregnancy outcome. The data of 11,755 singleton births that had taken place between 2010 and 2020 at the Public Clinic Donaustadt in Vienna, Austria, were analyzed. Birth weight, birth length, head circumference, APGAR scores, and pH values of the arterial umbilical cord blood described fetal growth as well as the vital parameters after birth. Gestational weight gain was classified as too low, recommended, or too high according to the different weight status categories of the IOM guidelines. Birth weight, birth length, and head circumference of the newborn were significantly increased (p < 0.001) among underweight, normal-weight, and overweight women who gained more weight than recommended. Among obese women, only birthweight was significantly (p < 0.001) higher among women who gained more weight than recommended. Furthermore, a too-high gestational weight gain was significantly associated with an increased risk of macrosomia and emergency cesarean sections among underweight, normal-weight, and overweight women, but not among obese ones. Obese and morbidly obese women experiencing excessive gestational weight gain showed no significantly increased risk of macrosomia or emergency cesarean section. However, among obese mothers, a too-low gestational weight gain reduced the risk of emergency cesarean sections significantly (p = 0.010). Consequently, the IOM recommendations for gestational weight gain fit only partly for pregnant women in Austria. In the case of obese and morbidly obese women, new guidelines for optimal pregnancy weight gain should be considered.
Keywords: emergency caesarean section; excessive gestational weight gain; intrauterine growth; newborn size; perinatal risks; pregnancy outcomes.