Uterine rupture risk remains low when attempting vaginal birth after cesarean delivery

Key takeaways:

• The absolute risk for uterine rupture with an attempted vaginal birth after cesarean delivery was 0.3%.
• Clinicians say benefits often outweigh any risks, but shared decision-making is important.

The rate of uterine rupture increased slightly over 12 years for women who attempted a vaginal birth after a prior cesarean delivery, although the absolute risk for such an outcome remains “exceedingly low,” researchers reported.

“As clinicians, we have patients who come to us after a prior C-section and want to know what they should do for their next pregnancy,” Ann M. Bruno, MD, MS, assistant professor in the department of obstetrics and gynecology, division of maternal-fetal medicine at University of Utah Health, told Healio. “Our counseling is about the options for a trial of labor after c-section vs. a repeat cesarean delivery. The most feared risk we have as clinicians is the risk for uterine rupture. Despite that risk, we still have patients who take this on every day. The historical rate for uterine rupture after one prior c-section has been quoted at about 0.6% across the literature. We wanted updated data to reassess what that looks like in a more modern time, with national data.”

In a repeated cross-sectional analysis, researchers analyzed 1,016,073 singleton deliveries between 2010 and 2022, using National Center for Health Statistics data. Included women attempted a vaginal birth after one or two prior cesarean deliveries. The primary outcome was uterine rupture; secondary outcomes included unplanned hysterectomy, maternal blood transfusion, maternal ICU admission, NICU admission and neonatal death.

The data were published in Obstetrics & Gynecology.

Within the cohort, uterine rupture occurred with 0.28% of the deliveries.

Women who experienced uterine rupture were more likely to be older, have gestational diabetes, a hypertensive disorder of pregnancy, undergo induction or augmentation of labor, and have two prior cesarean deliveries, according to the researchers. There was no association between maternal BMI and uterine rupture incidence.

Although rates were low throughout the observation period, researchers observed that uterine rupture rates increased from 0.2% in 2010-2014 to 0.37% in 2020-2022, for an annual percentage increase of 6.2% (95% CI, 4.3-8.7).

“We did find that the rate of uterine rupture increased over time; however, the rate of uterine rupture over the full study period is lower than what his historically been quoted,” Bruno told Healio.

Rates of transfusion and maternal ICU admission similarly increased over time, whereas the rate of unplanned hysterectomy did not change, according to the researchers.

The incidence of neonatal death fell during the study period, with an annual percentage decrease of 6.4% (95% CI, –8.5 to –3.8). The rate of NICU admission also increased, with an average annual percent change of 1.8% (95% CI, 1.3-2.2).

Bruno cautioned that the analysis was not a comparison of trial of labor vs. a repeat cesarean delivery. Rather, the researchers sought to collect updated statistics for a more accurate risk picture.

“This work is important, as it gives us this big picture on a national level on rates of uterine rupture and other complications,” Bruno told Healio. “I would like for us to conduct a prospective study collecting more nuanced clinical data on patients getting induced vs. coming in spontaneous labor, aspects of maternal care, maternal comorbid health conditions and other factors, to get at the details of associations with those other risk factors.”

Bruno said it is important that pregnant patients feel informed about the risks and benefits of a trial of labor after cesarean section delivery.

“The absolute risk [for uterine rupture] is about 0.3% across these data,” Bruno told Healio. “While we do not want to ignore that risk and it is important to counsel patients, we also want to emphasize that the absolute event rate is exceedingly low. Many of the benefits from trial of labor after cesarean and vaginal birth after cesarean outweigh that potential risk. That said, it is up to the patient to make that decision.”

For more information:

Ann M. Bruno, MD, MS, can be reached at ann.bruno@hsc.utah.edu; Bluesky: @annmbruno.bsky.social; Instagram: @ambruno4.