Effectiveness and safety of assisted vaginal birth and second-stage cesarean section: a systematic review and meta-analysis of real-world contemporary data.

Abstract

To synthesize evidence on the effectiveness of different instruments for assisted vaginal birth and to assess the prevalence of maternal and neonatal adverse outcomes associated with assisted vaginal birth and second-stage cesarean section. A comprehensive search was conducted in Cochrane, Embase, and MEDLINE to identify randomized controlled trials and cross-sectional and cohort studies published between January 2001 and December 2023. Studies published in English, Spanish, French, or Italian with >30 participants, conducted in any type of healthcare facility, and reporting operative procedures in the second stage of labor were eligible if they included at least one outcome of interest for women undergoing assisted vaginal birth and/or second-stage cesarean section. Two independent reviewers conducted study selection, data extraction, and quality assessment. Meta-analyses of proportions were performed using random-effects models, and heterogeneity was assessed using the I² statistic. A total of 241 studies, involving 751,242 participants, were included, of which 231 were observational and 10 randomized controlled trials. Prevalence estimates for assisted vaginal birth failure and adverse outcomes varied widely. Vacuum extraction had a significantly higher failure rate than forceps (7.60% vs 3.26%, P<.01), but a lower prevalence of obstetric anal sphincter injury (4.73% vs 7.99%, P<.01). Spatula use was associated with a lower prevalence of neonatal cephalohematoma compared to vacuum extraction (0.73% vs 5.45%, P<.01) and forceps (0.73% vs 3.54%, P<.01), but a higher prevalence of postpartum hemorrhage compared to vacuum extraction (10.77% vs 5.46%, P<.0001). Compared to assisted vaginal birth, second-stage cesarean section was associated with significantly higher rates of neonatal intensive care unit admission (17.18% vs 6.64% forceps, 6.07% vacuum extraction, P<.001), low Apgar scores (6.01% vs 2.43% forceps, 2.05% vacuum extraction, P<.01), skull fractures (1.54% vs 0.27% for both, P<.05), and neonatal death (1.95% vs 0.31% for both, P<.01). Contemporary data reveal wide variability in the prevalence of failed assisted vaginal birth and adverse maternal and neonatal outcomes following operative delivery in the second stage of labor. While assisted vaginal birth carries specific risks, it may offer advantages over emergency second-stage cesarean section, particularly regarding neonatal outcomes.