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Obstetric anal sphincter injuries (OASIs) are associated with significant short-term and long-term morbidity. Over the past decade, there has been a steady rise in the rate of OASIs. There is therefore a compelling need to identify strategies to minimize OASIs. The objective of this study was to determine if perineal support at the time of vaginal delivery can reduce the incidence and severity of OASIs.

All labour ward staff including midwives and doctors were invited to train in the technique of perineal support during vaginal delivery. Two experts from Norway conducted workshops with practical hands-on training on pelvic models. The midwives and doctors underwent further training with women in labour, and mandatory training was continued within the department. All midwives and doctors were instructed to support the perineum during both spontaneous and assisted vaginal delivery.

From April 2011 to November 2014, 11,135 women underwent vaginal delivery. The OASI rate decreased from 4.7 % to 4.1 % (p = 0.11). There was a significant reduction (0.9 % to 0.3 %, p < 0.001) in 3c third-degree and fourth-degree tears (major OASIs). In a multivariate analysis, perineal support was associated with a significant reduction in the rates of OASIs (23 %; OR 0.77, 95 % CI 0.63 - 0.95, p = 0.01]) and major OASIs (71 %; OR 0.34, 95 % CI 0.17 - 0.69, p = 0.03).

This interventional study showed that perineal support during vaginal delivery can reduce the risk of major OASIs. With sustained reinforcement of this intervention programme, we anticipate a further reduction in OASI rates.