METHODS: We performed a retrospective cohort study of 857 women who did not have obstetric risk factors. The association between hospital and cesarean delivery rate was examined in a multivariate analysis using logistic regression. In a follow-up cohort study, we observed labor management for 24 couples in the community and 26 in the tertiary hospital.
RESULTS: The odds of having a cesarean birth (age-adjusted) at the tertiary center were 3.4 (95% confidence interval, 2.1-5.4) compared with the community hospital. Maternal age, cervical dilatation on first examination, and use of epidural analgesia were the primary factors associated with the difference in cesarean delivery rates, with epidural analgesia having the largest effect. Labor support between the 2 hospitals appeared to be similar with the exception of increased use of ambulation in the community hospital and fewer numbers of caregivers for each woman in labor. Women in the tertiary center were more often offered epidural analgesia.
CONCLUSIONS: Differences in use of epidural analgesia may contribute to differences in institutional rates of cesarean delivery. Use of epidural analgesia may be related to use of ambulation, consistency of caregiver during labor, availability of epidural, and suggestion for its use by caregivers.
Although the seemingly relentless increase in cesarean delivery rates in North America in the 1970s and 1980s has stabilized in recent years and even reversed slightly in some regions,1 rates are still generally considered to be too high, and efforts to diminish them continue.2 In spite of accumulating evidence about the preventable causes of cesarean delivery, individual institutions have had difficulty changing practice.3 At BC Women’s Hospital, the largest maternity facility in Canada with 7500 births annually, the cesarean delivery rate in 1995 was 22.9%.4 Although BC Women’s is the referral/tertiary center for the province of British Columbia, 80% to 85% of the births occur to low-risk women in the surrounding catchment area of Vancouver. Approximately 30 obstetricians and 100 family practice physicians have admitting privileges. At nearby Burnaby Hospital, a community general hospital providing primary- and secondary-level maternity care, cesarean delivery rates were 10.3%.4 At Burnaby, 3 obstetricians and 38 family practice physicians deliver 2000 babies annually. At the time of our study, neither hospital had practicing midwives. The discrepancy in cesarean delivery rates between hospitals only 20 minutes’ driving distance apart afforded us the opportunity to look at differences in practice between the institutions.
In phase I we completed a retrospective cohort study using hospital records. Records were considered eligible if parturient women met the following criteria: nulliparous, maternal age 16 to 35 years, singleton gestation, and gestation of 37 completed weeks or longer. We excluded women with known pregnancy complications.
Charts were selected from a computer-generated list that incorporated inclusion and exclusion criteria and were then reviewed by a research nurse. Blinding as to hospital was not possible. Using this system, 430 nulliparous women from each hospital were selected consecutively. The sample size was calculated to be 430 per group to have 80% power with type I error set at 0.05, to determine a difference in cesarean delivery rate of 30% from a baseline of 23%. We examined the role of demographic and obstetric factors in the association between hospital and cesarean delivery rate. Maternal and fetal outcomes were measured, including postpartum hemorrhage and infection, as were APGAR scores at 5 minutes. We used logistic regression to simultaneously adjust for confounding factors.
Since we were not able to randomly allocate women to hospitals, it was important to determine if women giving birth at BC Women’s compared with Burnaby selfselected to either of the hospitals because of differing expectations for pain management in labor. We also wanted to discern if there were aspects of the care given during the intrapartum period that might explain differing rates of use of epidural analgesia. In the phase II observation study, a research assistant was assigned to observe consecutive women giving birth 2 days per week at each hospital. Our research assistant was a medical student who had not practiced in either hospital. Structured observations were recorded along with times for each observation period and the stage of labor at which the observation took place. The same inclusion and exclusion criteria were used as in our phase I retrospective study to ensure that we were observing comparable women without preexisting risk factors for cesarean delivery at the onset of labor. The phase II study did, however, include multiparous women to maximize use of the time the student was available to assist with the study.