Mediolateral episiotomy and risk of obstetric anal sphincter injuries and adverse neonatal outcomes during operative vaginal delivery in nulliparous women: a propensity-score analysis

Table 2 Association between mediolateral episiotomy and OASIs according to the type of operative vaginal delivery

	Total number of women^†	Mediolateral episiotomy		No Mediolateral episiotomy		RR (95% CI)
	Total number of women^†	Number of women	Number (%) with OASIs	Number of women	Number (%) with OASIs	Univariate analysis *	Using IPTW ^*
Whole population	7589	2880	52 (1.8)	4709	203 (4.3)	0.40 (0.29–0.56)	0.33 (0.27–0.41)
Forceps/spatula delivery	2698	1433	33 (2.3)	1265	86 (6.8)	0.34 (0.22–0.54)	0.38 (0.28–0.52)
Vacuum delivery	4853	1421	18 (1.3)	3432	117 (3.4)	0.31 (0.18–0.52)	0.27 (0.20–0.38)

RR risk ratio, CIs confidence intervals, IPTW inverse probability of treatment weighting, OASIs obstetric anal sphincter injuries. * Mixed model. ^† Missing data – mode of operative vaginal deliveries: n = 38. Covariates used to estimate the propensity score: induction of labour, epidural analgesia, occiput posterior position, prolonged pregnancy defined as > 41 weeks of gestation, fetal distress, type of instruments (forceps/spatula delivery and vacuum delivery), birth weight as a proxy of prenatal suspicion of large for gestational age, year of delivery and level of maternity unit

ISSN: 1471-2393