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

Abstract

OBJECTIVE To synthesize evidence on the effectiveness of different instruments for assisted vaginal birth (AVB) and to assess the prevalence of maternal and neonatal adverse outcomes associated with AVB and second-stage cesarean section (SCS). DATA SOURCES A comprehensive search was conducted in Cochrane, Embase, and MEDLINE to identify randomized controlled trials, cross-sectional, and cohort studies published between January 2001 and December 2023. STUDY ELIGIBILITY CRITERIA 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 AVB and/or SCS. STUDY APPRAISAL AND SYNTHESIS METHODS 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. RESULTS A total of 241 studies, involving 751,242 participants, were included, of which 231 were observational and 10 randomized controlled trials (RCT). Prevalence estimates for AVB failure and adverse outcomes varied widely. Vacuum extraction (VE) had a significantly higher failure rate than forceps (7.60% vs. 3.26%, p<0.01), but a lower prevalence of obstetric anal sphincter injury (4.73% vs. 7.99%, p<0.01). Spatula use was associated with a lower prevalence of neonatal cephalohematoma compared to VE (0.73% vs. 5.45%, p<0.01) and forceps (0.73% vs. 3.54%, p<0.01), but a higher prevalence of postpartum hemorrhage compared to VE (10.77% vs. 5.46%, p<0.0001). Compared to AVB, SCS was associated with significantly higher rates of NICU admission (17.18% vs. 6.64% forceps, 6.07% VE, p<0.001), low Apgar scores (6.01% vs. 2.43% forceps, 2.05% VE, p<0.01), skull fractures (1.54% vs. 0.27% for both, p<0.05), and neonatal death (1.95% vs. 0.31% for both, p<0.01). CONCLUSION Contemporary data reveal wide variability in the prevalence of failed AVB and adverse maternal and neonatal outcomes following operative delivery in the second stage of labor. While AVB carries specific risks, it may offer advantages over emergency SCS, particularly regarding neonatal outcomes.