Reduction has lasted over time
We believe that the change in clinical practice in Norway from the 1990s onwards, with less use of perineal protection during the second stage of labour, was a major reason for the unfavourable development. «Hands-off» philosophy, with increasing use of alternative birth positions with poor overview of the perineum and thereby inability to perform perineal protection during the second stage of delivery was the rule. The changes in delivery practice in Norway are poorly documented, and it is difficult to evaluate the effect of delivery position or perineal protection on the incidence of sphincter injuries retrospectively. The delivery techniques in Finland were not altered to the same extent, and Finland has had a much lower incidence of obstetric anal sphincter injuries than the other Nordic countries.
The Norwegian Board of Health criticised delivery units for high rates of obstetric anal sphincter injuries, and a national action plan to reduce the number of injuries was drawn up in 2006. The incidence of sphincter injuries was to be reduced from 4.1 % to 2 % within two years (3). The national plan recommended «focusing on protection techniques both in spontaneous and operative deliveries» (3), and in many Norwegian delivery units the delivery procedures were changed. Six maternity units in Norway have recently published similar significant reduction in frequency of anal sphincter injuries after implementation of an intervention programme. The intervention consisted of active management of the second stage of labour with standardised perineal protection and lowering the delivery speed of the baby’s head, as well as careful instruction of and communication with the woman in all vaginal deliveries (1, 4, 5).
In Norway, there has been a large decline in the incidence of sphincter injuries from 2004 to 2011, from 4.1 % to 2.1 % of all vaginal deliveries. This implies that 4,600 fewer women have suffered such an obste-tric delivery injury over the past seven years, compared to what the situation would have been without such a dramatic reduction in injury incidence. However, the Medical Birth Registry reports that the incidence varies widely between the hospitals, with a threefold higher incidence of sphincter injuries in hospitals with the highest incidence compared to hospitals with the low-est incidence. The Medical Birth Registry shows that the achieved incidence reduc-tion in sphincter injuries has lasted over time (1).