This study investigates the relative risk of obstetric complications stratified by pre-pregnancy body mass index (BMI) and pregnancy weight gain.METHODS:
This was a retrospective cohort study of 17,393 pregnant women with singleton births between January 2004 and May 2015. We stratified patients based on pre-pregnancy BMI category (as per the Institute of Medicine, IOM) and amount of weight gain (appropriate, less than or greater than recommended). Primary maternal outcomes included: gestational diabetes (GDM), preeclampsia, macrosomia, fetal growth restriction (FGR), and rates of cesarean delivery, shoulder dystocia, preterm delivery (PTD), blood loss and operative delivery. Primary neonatal outcomes included hypoglycemia, length of NICU stay, APGAR score at 5 minutes, and rate of respiratory distress syndrome (RDS).RESULTS:
The relative risk of GDM, preeclampsia, fetal macrosomia, cesarean delivery, blood loss, neonatal hypoglycemia and RDS increased with each successive BMI category. The risk for FGR mostly decreased with increasing BMI. Risks of other obstetric and neonatal complications did not appear to be correlated with increasing BMI category. FGR risk decreased with increasing weight gain for non-obese patients. For all classes of obesity, patient's weight gain was positively correlated with a higher risk of cesarean delivery and inversely proportional to the risk of PTD.CONCLUSION:
This large retrospective cohort study showed that as BMI category changed from I to II to III, there were significant increases in the rates of maternal and neonatal complications. In addition pregnancy complications are increased when weight gain does not conform to IOM recommendations.