Methods	Ralloc software (Boston College Department of Economics, Boston, MA) was used to create a random sequence of numbers in blocks with 2, 4, and 6 size permutations
Participants	446 nulliparous women with pregnancies more than 28 weeks of gestation who had vaginal deliveries
Interventions	Patients were assigned either to the routine episiotomy or the selective episiotomy group, depending on the basis of the randomization sequence kept at the institution. Patients assigned to the selective episiotomy group underwent the procedure only in cases of forceps delivery, fetal distress, or shoulder dystocia or when the operator considered that a severe laceration was impending and could only be avoided by performing an episiotomy. This decision was made by the treating physician. All the patients in the routine episiotomy group underwent the procedure at the time the fetal head was distending the introitus
Outcomes	The primary outcome of severe laceration to perineal tissues was defined as a third-degree laceration when the extent of the lesion included the external anal sphincter totally or partially, and fourth degree laceration when the rectal mucosa was involved.
Notes	Midline episiotomies. Epsiotomy rates were 24.3% for restricted group and 100% for the routine group
Risk of bias
Bias	Authors’ judgement	Support for judgement
Allocation concealment (selection bias)	Low risk	A - Adequate