Obesity as a risk factor for cesarean in a low-risk population

Objective: To determine whether low-risk maternity patients in a nurse-midw ifery service with prepregnant body mass index (BMI) above 29.0 are at incr eased risk for cesarean delivery. Methods: We studied 1881 women who delivered between 1994 and 1998 and were managed by an academic inner-city hospital-certified nurse-midwifery pract ice. We calculated prepregnancy BMI and weight gain during pregnancy by usi ng clinical data from a comprehensive clinical database, and did descriptiv e analyses and univariate and multivariate logistic regression analyses. Results: The overall cesarean rate was 5.1%, but was 7.7% for obese women c ompared with 4.1% for women with normal BMI (19.8-25.9). The unadjusted odd s ratio (OR) for cesarean for obese women was 2.02 (95% confidence interval [CI] 1.26, 3.25, P < .01). Other factors associated with increased risk of cesarean delivery included primigravidity, primiparity, maternal age 35 ye ars or older, short stature (height under 155 cm), very low birth weight in fant, failure to progress, breech presentation, abruption, fetal bradycardi a, and severe preeclampsia. Maternal race and marital status were not assoc iated with cesarean delivery. After adjustment for weight gain, short statu re, advanced maternal age, primiparity, and intrapartum complications, the OR for obesity was 3.99 (95% CI 2.00, 7.95, P < .001). Conclusion: Even among low-risk women managed by nurse-midwives, the risk o f cesarean delivery was higher for obese women. Short, obese women were at higher risk of cesarean delivery compared with women with normal BMIs, but were not high enough risk to preclude them from receiving nurse-midwifery c are. (Obstet Gynecol 2001;97:3943. (C) 2001 by The American College of Obst etricians and Gynecologists.)