Cesarean Delivery for Dystocia In Nulliparous Women
- Identify the national and regional U.S. data supporting an epidemic of both cesarean delivery and maternal overweight and obesity among nulliparous women.
- Describe the relationships identified in the literature between maternal BMI and labor and birth outcomes.
- Discuss the implications of the study findings for future research to understand the phenomenon of uterine dystocia among nulliparous women.
Design: A retrospective population cohort design.
Setting: University Level III perinatal unit.
Patients/Participants: 3,802 nulliparous women met the inclusion criteria.
Methods: Cohort study of all essentially healthy nulliparous women who delivered a singleton fetus at term gestation in a head down position over a 4 year period. The data source was the institutional database for all women who deliver at our University Hospital.
Results: For the 3,802 nulliparous women, there were 935 cesarean deliveries (24.6%), of which 222 occurred prior to labor (5.8% overall). Of 3,580 nulliparas who labored, 713 (19.9%) experienced cesarean. To study the relationship between BMI and dystocia during labor, the dataset was limited to those cases with data to compute pre-pregnancy BMI and total gestational weight gain leaving a sample of 3,347 nulliparas. These women had a mean age of 23.9 (+ 6) years; were predominantly single (51%) and racially distributed as 40% non-Hispanic White, 38.4% Hispanic, 14.5% Black, 4.2% Asian, and 2.9% other. The overall cesarean rate was 20.3%. A significantly increased rate of cesarean delivery from 15% to 35.2% (X2 = 61.8, 5 df, p <.001) occurred as BMI category increased from underweight to obese III (BMI > 40). There was no relationship between pregnancy weight gain and the incidence of cesarean. Overall, the cesarean indication was dystocia (66.8%), NRFHT (30.6%), and other (2.6%). The incidence of cesarean for dystocia increased significantly from 10.9% among underweight/normal weight, to 22.2% among obese nulliparous women (X2 = 45.7, 2 df, p <.001). Significant logistic regression predictors of cesarean were induction of labor; racial/ethnic minority designation; maternal age; and overweight or obese BMI.
Conclusion/Implications for nursing practice: The slightly lower rate of cesarean in this nulliparous population compared to the national rate of 26% (2006) is likely due to an emphasis on evidence-based care, a state with the nation’s lowest rates of obesity, and multidisciplinary providers with nurse-midwives attending approximately 40% of all births. Efforts to reduce women’s prepregnancy BMI are indicated as one strategy to decrease the rate of primary cesarean delivery. In vitro evidence suggests the need for research into biological links between adiposity and uterine function.
Keywords: dystocia, cesarean, nulliparous, body mass index
