Maternal morbid obesity and the risk of adverse pregnancy outcome.

OBJECTIVE To evaluate whether morbidly obese women have an increased risk of pregnancy complications and adverse perinatal outcomes. METHODS In a prospective population-based cohort study, 3,480 women with morbid obesity, defined as a body mass index (BMI) more than 40, and 12,698 women with a BMI between 35.1 and 40 were compared with normal-weight women (BMI 19.8-26). The perinatal outcome of singletons born to women without insulin-dependent diabetes mellitus was evaluated after suitable adjustments. RESULTS In the group of morbidly obese mothers (BMI greater than 40) as compared with the normal-weight mothers, there was an increased risk of the following outcomes (adjusted odds ratio; 95% confidence interval): preeclampsia (4.82; 4.04, 5.74), antepartum stillbirth (2.79; 1.94, 4.02), cesarean delivery (2.69; 2.49, 2.90), instrumental delivery (1.34; 1.16, 1.56), shoulder dystocia (3.14; 1.86, 5.31), meconium aspiration (2.85; 1.60, 5.07), fetal distress (2.52; 2.12, 2.99), early neonatal death (3.41; 2.07, 5.63), and large-for-gestational age (3.82; 3.50, 4.16). The associations were similar for women with BMIs between 35.1 and 40 but to a lesser degree. CONCLUSION Maternal morbid obesity in early pregnancy is strongly associated with a number of pregnancy complications and perinatal conditions. LEVEL OF EVIDENCE II-2