LOS ANGELES — Women who choose vaginal birth after a cesarean section have a 2.5 times greater risk of major complications than if they were to opt for a second elective cesarean section, according to a poster presentation at the annual meeting of the Society for Gynecologic Investigation.
The adjusted odds ratio of 2.5 for major morbidities comes from a retrospective cohort study, comparing 5,299 women who attempted vaginal birth after a cesarean (VBAC) section with 4,065 women who elected a second cesarean delivery. Major complications occurred in 295 women (6%) in the VBAC group and 101 women (3%) who delivered by a second C-section.
“I think we are … seeing a swing where more people are getting sectioned, and now we are going to see complications from the sections,” investigator Heather S. Lipkind, M.D., said in presenting the data.
Cesarean deliveries accounted for 27.3% of all births in 2003, while the VBAC rate plunged to a low of 10.6%, according to Dr. Lipkind, a fellow in maternal-fetal medicine at Columbia University College of Physicians and Surgeons in New York City, and her colleagues.
Dr. Lipkind and her associates reported that numerous studies have looked at VBAC complication rates, but none has been a randomized, controlled trial. Therefore, the researchers used propensity scores, a statistical technique, to approximate a trial by controlling for confounders resulting from the nonrandomized assignment of women to the VBAC or repeat C-section cohorts.
The patients came from a 5-year database of births at 17 university and community hospitals. All had a single gestation and one prior low-transverse cesarean delivery. None had previously given birth vaginally. Dr. Lipkind said the success rate was 68% for the women who attempted VBAC.
Rupture was the most common major complication, occurring in 106 (2%) VBAC patients, compared with 19 (less than 1%) patients who elected C-sections (adjusted odds ratio 4.8).
Although the other major complications occurred in less than 1% of both groups, bladder injury more than tripled in the VBAC cohort; it occurred in 27 VBACs and 7 repeat C-sections (adjusted odds ratio 3.5). Other major complications were hemorrhage (29 VBACs vs. 17 repeat cesareans; adjusted odds ratio 1.5) and abruption (65 VBACs vs. 39 repeat cesareans: adjusted odds ratio 1.4).
Minor complications were similar between groups: 757 (14%) in the VBAC cohort and 489 (12%) in the elective C-section patients (adjusted odds ratio 1.0). Fever was the most common, occurring in 626 (12%) women who chose VBAC and 424 (10%) women who had repeat C-sections (adjusted odds ratio 0.9).