Body mass index as a risk factor for cesarean delivery in the nulliparous parturient

Abstract

Objective: To evaluate the relationship between body mass index (BMI) and risk of cesarean delivery in a nulliparous population. Methods: The Mayo Medical Center obstetric delivery database for January 1993 to December 1999 was reviewed to identify all singleton nulliparous women. Height, pregestational weight, BMI, indication, and type of delivery were recorded. Statistical analyses were performed using the Student t test and χ 2 test. Results: Over the study interval, 12,521 deliveries were recorded: 4,302 (34.4%) occurred in nulliparous women with singleton births. Six hundred thirty-nine were excluded for the following reasons: 1) no maternal height recorded (n = 568) or 2) elective cesarean deliveries (n = 71). The overall cesarean rate for the entire study cohort of 3,663 was 17.0%. The cesarean delivery rate was not significantly different (16.9%; 192/1139) for those who underwent labor induction. Interestingly, the cesarean rate was significantly higher in overweight (BMI, 25–29) women (19.1%; 128/659) ( P = 0.038) and obese (BMI, > 29) women (23.6%; 124/525) ( P <0.0001) as compared with women of normal weight (BMI, 20–24.9) (15.5%; 296/1905). The cesarean rate in women with low BMI (<20) was lower (13.4%; 77/574); however, this was not significantly different from the rate observed in women of normal weight. Conclusion: Increased BMI is a risk factor for cesarean delivery in nulliparous women.