Objective: To study the effects of morbid obesity defined as a first trimester maternal body mass index of >40 on the perinatal outcome.
Methods: One hundred and eighty-eight singleton pregnancies of women with first trimester BMI >40 who delivered at Al-Mafraq Hospital, Abu Dhabi during 1996-1998 were studied. A control group of normal body mass index matched for age and parity were selected and the perinatal variables were compared between groups. Morbidly obese women with diabetes and hypertension antedating the index pregnancy were later excluded and the data were re-analyzed.
Results: Morbidly obese women were noted to have significantly adverse perinatal outcomes including hypertensive disorders of pregnancy (28.8 vs. 2.9%, P<0.0001), gestational diabetes (24.5 vs. 2.2%, P<0.0001), cesarean section (15.2 vs. 9.3%, P<0.05) and macrosomia (32.6 vs. 9.3%, P<0.001) compared to non-obese women. However, we noted a significantly lower rate of prematurity in the obese group (0.5 vs. 5.3%, P<0.001). Even when morbidly obese women with (a) diabetes and hypertension antedating the index pregnancy and (b) those who developed gestational diabetes and/or pregnancy-induced hypertension during the index pregnancy were excluded from the analysis, significant differences in the perinatal outcomes still persisted.
Conclusion: Morbid obesity appears to be an independent risk factor for adverse perinatal outcome.