Vaginal birth after cesarean revisited.

The U.S. total cesarean delivery rate has risen from 4 percent of deliveries in 1950 to 26 percent in 2002. 1 Concerned about the rising rate of cesarean deliveries, and noting that 98 percent of women with a prior cesarean section delivered by repeated cesarean section, a National Institutes of Health Consensus Development Task Force in 1980 recommended that “properly selected” women should be encouraged to labor and deliver vaginally after a prior cesarean delivery. 2 U.S. obstetricians and their patients were slow to respond to this call, but by the end of the 1980s, the rate of vaginal birth after prior cesarean delivery was clearly on the rise. However, after peaking at 28.3 percent in 1996, the rate fell steadily to 12.6 percent in 2002 in the wake of reports of uterine ruptures and their catastrophic consequences. The decline in the U.S. rate of vaginal birth after prior cesarean delivery was well established by the time a large study from Washington State was published in 2001. 3 That study of more than 20,000 women with a single prior cesarean delivery compared the risk of uterine rupture among women who underwent elective repeated cesarean delivery with that among women with spontaneous onset of labor and attempted vaginal delivery from 1987 to 1996. The rate of uterine rupture associated with the spontaneous onset of labor was significantly higher than that associated with repeated cesarean delivery without labor (5.2 per 1000 vs. 1.6 per 1000). Among the 91 women with uterine rupture, there were five perinatal deaths (5.5 percent), as compared with a perinatal mortality rate of 0.5 percent among women who did not have uterine rupture. Subsequently, Smith et al. reported a large study including all singleton deliveries with cephalic presentation in Scotland from 1992 to 1997. 4 Among women with one or more prior cesarean deliveries, the perinatal mortality rate was significantly higher among those who attempted labor than among those who delivered by planned repeated cesarean section (12.9 per 10,000 vs. 1.1 per 10,000). A strength of population-based studies that report results for an entire state or country is that they report “real world” results achieved across a wide spectrum of patients and patient care settings for very large numbers of subjects. However, they have been retrospective, have lacked consistent prespecified definitions of outcome measures, and have relied on vital records or administrative databases that have the potential for incomplete ascertainment and misclassification. Furthermore, women and providers who choose to attempt vaginal delivery may be different in important ways from those who choose elective repeated cesarean delivery. Smaller studies from individual centers that have better data quality by means of direct access to patient records have not had adequate power to address uncommon outcomes such as perinatal death. An assessment prepared in 2003 for the U.S. Agency for Healthcare Research and Quality regarding the practice of vaginal birth after cesarean delivery noted that “patients, clinicians, insurers, and policymakers do not have the data they need to make truly informed decisions about appropriate delivery choices following one of the most common surgical procedures performed on women.” 5