Intra-partum care of the perineum matters: new knowledge and remaining gaps.

The prevalence of obstetric anal sphincter injuries (OASIS) varies between hospitals and countries from rates below 1% to over 5%. In Europe there is a North - South gradient (Blondel et al, Acta Obstet Gynecol Scand. 2016; 95:746-54). Variations of prevalence are reported to be related to three factors: (i) insufficient diagnosis in very low prevalence settings; (ii) geographical variations in elasticity of the perineum such as, though there is some controversy, greater fragility in women from Asia; and (iii) management of the perineum at birth. For this determinant, two components have been challenged: reluctance to perform episiotomy and the "hands off" technique, practices adopted with enthusiasm in some countries and settings, possibly within the "minimize unnecessary intervention at birth" philosophy.