Objective: To review systematically techniques proposed to prevent perineal trauma during childbirth and meta-analyze the evidence of their efficacy from randomized controlled trials.
Data sources: MEDLINE (1966-1999), the Cochrane Library (1999 Issue 1), and the Cochrane Collaboration: Pregnancy and Childbirth Database (1995); and reference lists from articles identified. Search terms included childbirth or pregnancy or delivery, and perineum, episiotomy, perineal massage, obstetric forceps, vacuum extraction, labor stage-second. No language or study-type constraints were imposed.
Study selection: Randomized controlled trials (RCTs) of interventions affecting perineal trauma were reviewed. If no RCTs were available, nonrandomized research designs such as cohort studies were included. Studies were selected by examination of titles and abstracts of more than 1,500 articles, followed by analysis of the methods sections of studies that appeared to be RCTs. INTEGRATION AND RESULTS: Eligible studies used random or quasirandom allocation of an intervention of interest and reported perineal outcomes. Further exclusions were based on failure to report results by intention to treat, or incomplete or internally inconsistent reporting of perineal outcomes. Final selection of studies and data extraction was by consensus of the first two authors. Data from trials that evaluated similar interventions were combined using a random effects model to determine weighted estimate of risk difference and number needed to treat. Effects of sensitivity analysis and quality scoring were examined. Results indicated good evidence that avoiding episiotomy decreased perineal trauma (absolute risk difference -0.23, 95% confidence interval [CI] -0.35, -0.11). In nulliparas, perineal massage during the weeks before giving birth also protected against perineal trauma (risk difference -0.08, CI -0.12, -0.04). Vacuum extraction (risk difference -0.06, CI -0.10, -0.02) and spontaneous birth (-0.11, 95% CI -0.18, -0.04) caused less anal sphincter trauma than forceps delivery. The mother's position during the second stage has little influence on perineal trauma (supported upright versus recumbent: risk difference 0.02, 95% CI -0.05, 0.09).
Conclusion: Factors shown to increase perineal integrity include avoiding episiotomy, spontaneous or vacuum-assisted rather than forceps birth, and in nulliparas, perineal massage during the weeks before childbirth. Second-stage position has little effect. Further information on techniques to protect the perineum during spontaneous delivery is sorely needed.