Objectives: Inadequate or excessive gestational weight gain (GWG) increases the risk of adverse outcomes associated with pregnancy. We aim to explore the association between GWG and adverse events during pregnancy.
Materials and Methods: A retrospective study was conducted to evaluate the perinatal outcomes in singleton women
whose weight gain during pregnancy was below, within, or above the 2009 Institute of Medicine's (IOM) guidelines, and
delivered between 24 and 42 weeks' gestation. GWG was derived using weight at delivery minus the pre-pregnancy or
first trimester weight.  Results: Mothers with low GWG had increased odds of having small-for-gestational-age neonates (adjusted OR 1.202; 95% CI 1.031-1.403), and preterm birth (adjusted OR 2.03; 95% CI 1.769-2.439), but decreased odds of having macrosomia (adjusted OR 0.523; 95% CI 0.24-0.991). Mothers with GWG above the IOM recommendations had higher odds of having hypertensive disease of pregnancy (adjusted OR 2.07; 95% CI 1.314-3.535), gestational diabetes (adjusted OR 1.227; 95% CI 1.038-1.448), cesarean section (adjusted OR 1.34; 95% CI 1.279-1.512), induced labor (adjusted OR 1. 219; 95% CI 1.051-1.409), failure of induced labor (adjusted OR 1.432; 95% CI 1.03-1.992), macrosomia (adjusted OR 1.987; 95% CI 1.384-2.725), shoulder dystocia (adjusted OR 1.715; 95% CI 1.292-2.18), and treatment for neonatal hypoglycemia (adjusted OR 1.742; 95% CI 1.229-2.506).  Conclusion: GWG is an important predictor of adverse maternal and neonatal outcomes during pregnancy.