The full text of the article "Contemporary cesarean delivery practice in the United States" published on-line in the American Journal of Obstetrics and Gynecology reveals some interesting insights into the particulars of the study. Birth Story published an earlier post this week based on the abstract.
"The national rate of cesarean delivery in the United States has increased more than 50 percent since 1996, to 31.8 percent in 2007," the report states. "This upward trajectory appears likely to continue in the near future."
The study was performed as part of the Consortium on Safe Labor, an initiative of the National Institute of Child Health and Human Development. It used electronic medical records of 228,668 births at 19 American hospitals between 2002 and 2008.
Here are some highlights:
A total of 93 percent of babies who presented "nonvertex" — with any body part other than the head in the lead— came into the world via C-section. Almost 66 percent of multiples — twins or more — were delivered by cesearean section. Most of these moms did not attempt a trial of labor. The C-section rate doubled from 21 percent at age 20 to 42 percent after age 35, "mainly due to repeat pre-labor cesarean deliveries." Half of cesareans performed once labor had begun were because of "failure to progress" or the belief that the baby's head was too large for the mother's pelvis. More than a quarter were performed because of "fetal distress." Among women who had had previous deliveries, most C-sections occurred before labor began, and that was true no matter when they delivered. More than 60 percent of deliveries at 28 weeks gestation were C-sections. That rate went down as pregnancies progressed. The trial of labor in women with a uterine scar was 48 percent in 1999, 31 percent in 2002, and 29 percent by 2007. The success rate of vaginal births after cesarean (VBAC) in the study was 57 percent (of the 28 percent of women who attempted a VBAC), "markedly lower" than in "previous large studies," which had ranged as high as 87 percent. Overall, 84 percent of women with a uterine scar delivered by C-section. Pre-labor repeat C-sections "have a profound impact on the overall cesarean rate." "Truly elective" cesareans accounted for 9.6 percent of C-sections before labor commenced, and 2.1 percent undertaken during labor. The hospitals in the study represented a wide range in rates of C-sections, from 20 to 44 percent. Nearly 10 percent of the women who participated in the study added more than one delivery to the database; only the first delivery for each was included in the analysis. Two of the hospitals in the study were non-teaching community hospitals. Nine were teaching community hospitals and eight were university-affiliated teaching hospitals.