Failed vacuum and preterm delivery risk in the subsequent pregnancy: a multicenter retrospective cohort study

Abstract

Background: Second-stage cesarean delivery is associated with subsequent preterm delivery. Failed vacuum-assisted delivery is a subgroup of second-stage cesarean delivery in which the fetal head is engaged deeper in the pelvis and, thus, is associated with an increased risk of short-term maternal complications.

Objective: This study aimed to investigate the maternal and neonatal outcomes of women at their subsequent delivery after a second-stage cesarean delivery with failed vacuum-assisted extraction vs after a second-stage cesarean delivery without a trial of vacuum-assisted extraction.

Study design: This was a multicenter retrospective cohort study. The study population included all women in their subsequent pregnancy after a second-stage cesarean delivery who delivered in all university-affiliated obstetrical centers (n=4) in a single geographic area between 2003 and 2021. Maternal and neonatal outcomes of women who had second-stage cesarean delivery after a failed vacuum-assisted delivery were compared with women who had second-stage cesarean delivery without a trial of vacuum-assisted delivery. The primary outcome of this study was preterm delivery at <37 weeks of gestation. The secondary outcomes were vaginal birth rate and other adverse maternal and neonatal outcomes. Univariate analysis was followed by multiple logistic regression modeling.

Results: During the study period, 1313 women met the inclusion criteria, of whom 215 (16.4%) had a history of failed vacuum-assisted delivery at the previous delivery and 1098 (83.6%) did not. In univariate analysis, women with previously failed vacuum-assisted delivery had similar preterm delivery rates (<37, <34, <32, and <28 weeks of gestation), a successful trial of labor after cesarean delivery rates, uterine rupture, and hysterectomy. However, multivariable analyses controlling for confounders showed that a history of failed vacuum-assisted delivery is associated with a higher risk of preterm delivery at <37 weeks of gestation (adjusted odds ratio, 2.05; 95% confidence interval, 1.11-3.79; P=.02), but not with preterm delivery at <34 or <32 weeks of gestation.

Conclusion: Among women with a previous second-stage cesarean delivery, previously failed vacuum-assisted delivery was associated with an increased risk of preterm delivery at <37 weeks of gestation in the subsequent birth.

Keywords: cesarean delivery; complications; failed vacuum; maternal outcomes; preterm delivery; second-stage cesarean.