Maternal Morbid Obesity and the Risk of Adverse Pregnancy Outcome

Abstract

Obesity, including morbid obesity, is increasing rapidly in fertile women. Both maternal overweight and obesity are known to carry adverse pregnancy outcomes, including preeclampsia, gestational diabetes, and stillbirths. There are indications that morbid obesity, defined as a body mass index (BMI) exceeding 40 kg/m 2 , is associated with even more complications and adverse outcomes. This prospective population-based cohort study was designed to estimate the risk of poor perinatal outcomes in morbidly obese women. A total of 3480 such women were compared with 12,698 obese women whose BMI ranged from 35.1 to 40 kg/m 2 and with 535,900 women of normal body weight (BMI, 19.8-26 kg/m 2 ). Only singleton pregnancies were analyzed. Compared with normal-weight women, preeclampsia was increased nearly 5-fold in morbidly obese women (odds ratio [OR], 4.82). Obese women had an OR for preeclampsia of 3.90. Morbid obesity correlated with a nearly 3-fold increase in antepartum births compared with normal-weight women (OR, 2.79). There was no increase in the risk of abruptio placentae, and placenta previa was less frequent in morbidly obese women. Morbid obesity increased the risk of cesarean delivery nearly 3-fold compared with normal-weight women. Instrumental deliveries were increased 34% in the morbidly obese group and 18% in obese women. Morbidly obese women were likelier to have labor induced, even after excluding those with preeclampsia (OR, 2.38). Large-forgestational-age infants were almost 4 times more frequent in the morbidly obese group than in normal-weight women. The risk of having a small-for-gestational-age infant was also increased (but not when preeclamptic women were excluded). Fetal distress and low Apgar scores were more than twice as frequent in infants of morbidly obese women. Meconium aspiration was also more prevalent (OR, 2.85). This large-scale study strongly associates morbid obesity in parturients with numerous threatening complications, warranting a designation of at-risk pregnancy. Hopefully, this will prove to be a convincing argument favoring weight reduction before and during pregnancy, and possibly afterward as well.