[Perineal consequences according to obstetric practices: A comparative study here and elsewhere, Canada and France]

To study how differences in birth management can influence the frequency and types of perineal lesions.

We compared outcomes and obstetric practices during labour and birth in low-risk primiparous women in two maternity units: one Canadian (maternitA Sainte-Justine, Montreal, Quebec), one French (maternité Cochin-Port-Royal, Paris). We compared the occurrence of perineal lesions--episiotomy and severe perineal tear--in these two maternity units according to delivery method. Furthermore, we studied risk factors for perineal lesions using univariate and multivariate analyses.

Among the 1044 births in Montreal and the 1154 births in Paris, the Caesarian-section rate, about 19%, was comparable in both maternity units. Among primiparous women who had a vaginal delivery, the rate of instrumental extraction was higher in the French unit than in the Canadian one (28.2% vs. 21.5%, P < 0.001). The rate of episiotomy was significantly higher in the French unit (65.9%) than in the Canadian one (23.2%), whether the vaginal delivery was spontaneous (OR adjusted = 5.8 [4.4-7.7]) or assisted (OR adjusted = 120.2 [61.0-23.1]). The rate of severe perineal tear was significantly higher in the Canadian maternity unit (11.1%) than in the French one (1.3%), whether the vaginal delivery was spontaneous (OR adjusted = 17.4 [2.4-128.7]) or assisted (OR adjusted = 45.7 [6.1-343.4]).

The significant differences in episiotomy and severe perineal tear rates observed in low-risk primiparous women are in part due to the different methods used to manage delivery in these two maternity units, particularly with regard to the angle of incision during episiotomy: median in Canada and median-lateral in France.