Second-stage cesarean deliveries may increase spontaneous preterm birth risk

Key takeaways:

• Spontaneous preterm birth rate was higher after second-stage cesarean delivery vs. vaginal delivery.
• Second-stage cesarean delivery doubled risk for spontaneous preterm birth vs. vaginal delivery.

Undergoing second-stage cesarian deliveries where mothers are at full cervix dilation, may increase the risk for subsequent spontaneous preterm birth vs. vaginal delivery, according to a systematic review and meta-analysis.

“Given the observed relationship between second-stage cesarean delivery and subsequent preterm birth, there may be potential to reduce excess risk of preterm birth by increasing the use of operative vaginal delivery,” Abirami Kirubarajan, MD, MSc, second-year resident in the department of obstetrics and gynecology at McMaster University in Hamilton, Ontario, Canada, and colleagues wrote. “The association between second-stage cesarean delivery is concerning since the rate of second-stage cesarean delivery is on the rise in several settings alongside a decrease in operative vaginal delivery.”

Kirubarajan and colleagues searched multiple databases for this systematic review and meta-analysis, published in the American Journal of Obstetrics & Gynecology, from inception to April 2023. The authors identified 18 retrospective cohort studies that included 605,138 women who underwent second-stage cesarean delivery or operative vaginal delivery with reported preterm birth rates in subsequent pregnancy.

After second-stage cesarean delivery, the pooled spontaneous preterm birth rate in subsequent pregnancies was 6.9% compared with 2.6% after operative vaginal delivery.

The authors observed a twofold higher risk for spontaneous preterm birth with second-stage cesarean delivery compared with operative vaginal delivery (OR = 2.01; 95% CI, 1.57-2.58) among the seven studies comparing the two. These studies also demonstrated a spontaneous preterm birth rate of 5.2% with second-stage cesarean delivery compared with 3% for operative vaginal delivery.

According to the authors, most studies did not include important confounding factors, failed to address exposure misclassification due to failed operative vaginal delivery and considered operative vaginal delivery a homogenous category without distinction between forceps and vacuum.

“There may be benefit to debriefing with patients following an operative delivery regarding the potential association with increased subsequent preterm birth, if patients are interested in multiple pregnancies,” the authors wrote. “There may also be benefit in screening the cervical length of these patients with transvaginal ultrasound in subsequent pregnancies, particularly as there is a growing trend towards universal screening of second-trimester cervical length for all pregnancies.”