Table 1.
Overview of included studies
| Authors (year) | Study type | Episiotomy type | Episiotomy incidence (%) |
Parity | Instrument type | OASI incidence (%) | OR [95% CI] |
|---|---|---|---|---|---|---|---|
| Ampt et al. [54] (2013) | Retrospective case control | MLE | 55.2 | All- separated | Both-separated | 7.2 | 1.07 [1.02, 1.14] |
| Aukee et al. [34] (2006) | Retrospective case control | MLE | 84.0 | All- pooled | Ventouse | 3.8 | 0.36 [0.13, 0.98] |
| Baghurst et al. [35] (2012) | Retrospective cohort | MLE | 55.0 | All- separated | Both-separated | 7.5 | 1.12 [0.96, 1.31] |
| Bodner-Adler et al. [36] (2018) | Retrospective cohort | MLE | 65.0 | Nulliparous | Ventouse | 6.8 | 0.60 [0.31, 1.16] |
| Boujenah et al. [37] (2019) | Retrospective cohort | MLE | 76.9 | Nulliparous | Both-separated | 2.8 | 0.38 [0.20, 0.74] |
| D'Souza et al. [38] (2020) | Retrospective cohort | MLE | 81.9 | Multiparous | Both-separated | 6.0 | 0.08 [0.01, 0.51] |
| De Leeuw et al. [39] (2008) | Retrospective cohort | MLE | 82.2 | All- separated | Both-separated | 3.4 | 0.14 [0.12, 0.16] |
| De Parades et al. [28] (2004) | Prospective cohort | MLE | 95.7 | Nulliparous | Forceps | 12.9 | 0.42 [0.04, 4.43] |
| De Vogel et al. [40] (2012) | Retrospective cohort | MLE | 81.0 | All- separated | Both-separated | 5.7 | 0.18 [0.13, 0.25] |
| Gachon et al. [41] (2019) | Retrospective cohort | MLE | 40.3 | All- separated | Both-separated | 7.4 | 0.38 [0.26, 0.55] |
| Gurol-Urganci et al. [33] (2014) | Retrospective cohort | MLE | 76.1 | Nulliparous | Both-separated | 7.1 | 0.49 [0.48, 0.51] |
| Hamouda et al. [27] (2017) | Prospective cohort | MLE | 58.2 | All- pooled | Both-separated | 3.9 | 1.08 [0.38, 3.10] |
| Jango et al. [42] (2014) | Retrospective cohort | MLE | 28.7 | Nulliparous | Both-separated* | 13.7 | 0.67 [0.63, 0.72] |
| Levin et al. [43] (2020) | Retrospective cohort | MLE | 78.0 | Nulliparous | Ventouse | 2.3 | 0.56 [0.35, 0.91] |
| Macleod et al. [29] (2008) | Prospective cohort | MLE | 78.4 | Nulliparous | Both-separated | 9.9 | 1.44 [0.88, 2.34] |
| Marschalek et al. [44] (2018) | Retrospective cohort | MLE | 72.5 | Nulliparous | Both-separated | 5.2 | 0.68 [0.60, 0.76] |
| Meyer et al. [53] (2020) | Retrospective cohort | MLE | 74.1 | All- separated | Forceps | 2.5 | 1.80 [0.52, 6.26] |
| Murphy et al. [25] (2009) | RCT | MLE | 72.0 | Nulliparous | Both-separated† | 10.9 | 4.79 [0.22, 105.30] |
| Parnell et al. [30] (2001) | Prospective case control | MLE | 53.0 | Nulliparous | Ventouse | 21.0 | 0.74 [0.41, 1.34] |
| Räisänen et al. [45] (2012) | Retrospective cohort | LE | 84.9 | All- separated | Ventouse | 3.0 | 0.47 [0.35, 0.64] |
| Räisänen et al. [46] (2009) | Retrospective cohort | LE | 90.0 | All- separated | Both-separated† | 1.5 | 1.09 [0.87, 1.36] |
| Rognant et al. [47] (2012) | Retrospective cohort | MLE | 85.0 | All- pooled | Ventouse | 2.2 | 1.97 [0.60, 6.48] |
| Rygh et al. [31] (2014) | Prospective cohort | MLE/LE | 55.0 | Nulliparous | Both-pooled | 11.0 | 0.72 [0.60, 0.87] |
| Sagi-Dain [26] (2020) | RCT | MLE | 49.6 | Nulliparous | Ventouse | 3.7 | 0.67 [0.11-4.12] |
| Schmitz et al. [44] (2014) | Retrospective case control | MLE | 66.5 | All- separated | Both-separated† | 2.1 | 0.04 [0.00, 0.79] |
| Shmueli et al. [49] (2017) | Retrospective cohort | MLE | 66.0 | All- separated | Ventouse | 1.5 | 1.73 [0.99, 3.04] |
| Van Bavel et al. [50] (2018) | Retrospective cohort | MLE | 89.6 | All- separated | Both-separated | 4.2 | 0.19 [0.18, 0.19] |
| Van Roon et al. [32] (2015) | Prospective cohort | MLE | 90.0 | Nulliparous | Both-pooled | 5.4 | 3.18 [1.39, 7.27] |
| Vathanan et al. [55] (2014) | Retrospective cohort | MLE | 78.7 | All-pooled | Both-separated | 9.2 | 0.18 [0.13-0.25] |
| Yamasato et al. [51] (2016) | Retrospective cohort | MLE | 3.7 | All- pooled | Both-separated | 21.7 | 0.65 [0.14, 3.09] |
|
Youssef et al. [52] (2005) |
Retrospective cohort | MLE | 71.2 | All- pooled | Both-separated | 8.7 | 0.99 [0.54, 1.81] |
RCT: randomised controlled trial
MLE- mediolateral episiotomy
L/E: lateral episiotomy
*Only data for ventouse deliveries reported, unable to retrieve crude data for forceps-assisted deliveries from authors
†Data not extractable, data retrieved from previous systematic reviews [14, 15] as unable to retrieve crude data from authors