Risk factors for episiotomy during vaginal birth: A systematic review and meta-analysis
Clinical Snapshot
PICO Framework
| P — Population | Women undergoing vaginal birth (across all parity groups and healthcare settings) |
| I — Intervention | Exposure to candidate risk factors: high newborn birth weight, oxytocin use, advanced maternal age, type of childbirth attendant, prolonged second stage of labour, and other reported factors |
| C — Comparator | Women without the identified risk factor(s) who underwent vaginal birth without episiotomy |
| O — Outcomes | Receipt of episiotomy during vaginal birth (primary outcome); odds ratios for individual risk factors as pooled effect estimates |
Bottom Line
This systematic review and meta-analysis of 16 observational studies (n=17,502) identifies high newborn birth weight (OR 2.39) and intrapartum oxytocin use (OR 2.34) as statistically significant risk factors for episiotomy during vaginal birth. Maternal age, type of birth attendant, and duration of the second stage of labour were not significantly associated with episiotomy in pooled analyses. While the findings are clinically plausible and the pooled sample size is reasonable, the evidence base carries important limitations: all included studies are observational, risk of bias assessment methodology is not transparently reported, GRADE certainty of evidence is absent, and the study population is predominantly drawn from Chinese tertiary obstetric settings. Generalisability to Australian and other Western healthcare contexts — where episiotomy rates, obstetric practices, and population demographics differ substantially — is uncertain. These results should be interpreted as hypothesis-generating rather than practice-defining. Clinicians should continue to apply restrictive episiotomy policies consistent with RANZCOG and WHO guidance, use shared decision-making, and await higher-quality prospective studies before attributing causal significance to these associations.
Key Findings
P Value: Newborn weight: P<0.001; Oxytocin use: P<0.001; Maternal age: P=0.466; Childbirth attendant type: P=0.733; Second stage duration: P=0.314
Effect Size: Newborn weight: OR 2.393 (significant); Oxytocin use: OR 2.341 (significant); Maternal age: OR 0.978 (non-significant); Type of childbirth attendant: OR 0.920 (non-significant); Duration of second stage of labour: OR 1.299 (non-significant)
Primary Outcome: Episiotomy during vaginal birth — pooled odds ratios for five candidate risk factors across 16 studies (n=17,502)
Nnt Or Sensitivity: Odds ratios reported throughout; no NNT, absolute risk difference, or attributable risk calculated. The OR of ~2.4 for both newborn weight and oxytocin use indicates approximately 2.4-fold increased odds of episiotomy in exposed versus unexposed women, though baseline episiotomy rates vary substantially across settings and are not standardised in this review.
Confidence Interval: Newborn weight: 95% CI 1.627–3.520; Oxytocin use: 95% CI 1.652–3.318; Maternal age: 95% CI 0.922–1.038; Childbirth attendant type: 95% CI 0.569–1.488; Second stage duration: 95% CI 0.781–2.162
Clinical Application
The identified risk factors (high newborn weight and oxytocin use) are clinically identifiable antenatally or intrapartum, making them potentially useful for risk stratification and informed consent discussions. However, the observational nature of the evidence means these associations should not be used to justify routine episiotomy in the presence of these factors. Shared decision-making and restrictive episiotomy policies remain the standard of care. In Australia, episiotomy practice is governed by RANZCOG guidelines, which recommend restrictive (not routine) episiotomy use. The Australian Institute of Health and Welfare (AIHW) reports episiotomy rates of approximately 22–25% in primiparous women nationally. Oxytocin (Syntocinon) is TGA-approved and widely used for labour augmentation and induction on the PBS. The findings regarding oxytocin use and macrosomia as risk factors are clinically plausible in the Australian context, but the predominantly Chinese study population limits direct applicability. RACGP and RANZCOG practitioners should interpret these findings cautiously and within the framework of existing restrictive episiotomy guidelines. No PBS or TGA policy changes are warranted on the basis of this evidence alone. Women undergoing vaginal birth in any healthcare setting, particularly those with macrosomic fetuses or requiring oxytocin augmentation/induction. Findings are most directly applicable to settings with episiotomy rates and obstetric practices comparable to those in the included studies (predominantly Chinese tertiary obstetric units).
Abstract
BACKGROUND: Despite the numerous harms associated with episiotomy during vaginal birth, the risk factors for this procedure remain a topic of controversy. This study aimed to identify the potential risk factors for episiotomy during vaginal birth. METHODS: A systematic search was conducted across 7 databases, including PubMed/MedLine, Embase, Cochrane, Web of Science, Chinese Knowledge Infrastructure (CNKI), and Wanfang, up to January 2025. Statistical analyses, including heterogeneity tests, sensitivity analysis, and publication bias assessment, were conducted using Stata 18.0 and Review Manager 5.4. RESULTS: A total of 16 articles were included in this meta-analysis, comprising a sample size of 17,502 individuals. Newborn weight (odds ratio [OR] = 2.393; 95% confidence interval [CI] = 1.627-3.520; P < .001) and oxytocin use (OR = 2.341; 95% CI = 1.652-3.318; P < .001) were identified as significant risk factors for episiotomy. In contrast, maternal age (OR = 0.978; 95% CI = 0.922-1.038; P = .466), the type of childbirth attendant (OR = 0.920; 95% CI = 0.569-1.488; P = .733), and the duration of the second stage of labor (OR = 1.299; 95% CI = 0.781-2.162; P = .314) were not statistically significant risk factors for episiotomy. CONCLUSION: High newborn weight and oxytocin use are associated with higher rates of episiotomy. However, other potential risk factors are still controversial due to a lack of sufficient evidence, highlighting the need for more rigorous studies to strengthen the evidence base.
References
- 1.He, X., Lu, D., Ou, R., & Feng, J. (2026). Risk factors for episiotomy during vaginal birth: A systematic review and meta-analysis. Medicine. https://doi.org/10.1097/MD.0000000000049662
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