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Table 4 Comparison of OASIS with or without episiotomy according to classification, vaginal deliveries, 2011–2016

From: A novel classification for evaluating episiotomy practices: application to the Burgundy perinatal network

Classification of episiotomy practices OASIS  
Without episiotomy With episiotomy P a OR IC 95% P
n/N % n/N %
1 – Nulliparous women with a single cephalic pregnancy, at ≥37 weeks gestation, non- instrumental delivery 206/17,395 1.2 37/4844 0.8 0.01 0.6 [0.4–0.9] 0.01
2 – Nulliparous women with a single cephalic pregnancy, at ≥37 weeks gestation, instrumental delivery 212/5307 4.0 59/3677 1.6  0.001 0.4 [0.3–0.5] 0.001
 2a -forceps/ spatula delivery 101/1642 6.2 46/2089 2.2 0.001 0.3 [0.2–0.5] 0.001
 2b -vacuum delivery 111/3665 3.0 13/1588 0.8  0.001 0.3 [0.1–0.5] 0.001
3 - Multiparous women with a single cephalic pregnancy, at ≥37 weeks gestation, non-instrumental delivery 110/39,347 0.3 12/2582 0.5 0.09 1.7 [0.9–3.0] 0.09
4 – Multiparous women with a single cephalic pregnancy, at ≥37 weeks gestation, instrumental delivery 51/1960 2.6 9/717 1.3 0.04 0.5 [0.2–0.9] 0.04
 4a - forceps/ spatula delivery 18/455 4.0 6/390 1.5 0.04 0.4 [0.1–0.9] 0.04
 4b - vacuum delivery 33/1505 2.2 3/327 0.9 0.18 0.4 [0.1–1.3] 0.14
5 – All women with a single cephalic pregnancy, at < 37 weeks gestation 10/3000 0.3 2/374 0.5 0.63 1.6 [0.3–7.4] 0.54
6 – All women with a single breech pregnancy 4/1043 0.4 1/225 0.4 1 1.2 [0.1–10.4] 0.89
7 – All women with multiple pregnancy 2/676 0.3 2/143 1.4 0.14 4.8 [0.7–34.2] 0.11
Total 595/68,728 0.9 122/12,562 1.0 0.25 1.1 [0.9–1.4] 0.24
  1. OASIS obstetric anal sphincter injuries. OR odds ratio
  2. aFisher’s exact tests