Included studies on the ‘Finnish intervention’
| Study | Study design | Data providers | Population | Comparator groups | Inclusion and exclusion criteria | Primary outcome | Secondary outcomes |
|---|---|---|---|---|---|---|---|
| Pirhonen et al 19985 | Register study | Skåne University Hospital, Malmö, Sweden, and Turku University Hospital, Finland | 30 933 births | 1990–1994 | Unknown | OASIS: Significantly lower frequency of OASIS in Finland (0.36%) compared to Sweden (2.69%) (p<0.001) | Apgar score after 5 min: Lower Apgar score in Finland compared to Sweden (p<0.01), caused by differences in the use of instrumental delivery |
| Length of second stage of labour: Prolonged second stage in Finland compared to Sweden (p<0.05) | |||||||
| Episiotomy: Significantly more usage of episiotomy in Finland (37.2%) compared to Sweden (24.3%) (p<0.001) | |||||||
| Laine et al 200828 | Before-and-after study | Oestfold Trust Hospital, Norway | 12 369 births | 2002–2007 | All births in one obstetric unit | OASIS: Significantly lower frequency of OASIS after implementation from 4.03% to 1.17% (p<0.001) | OASIS at instrumental deliveries: Significantly lower OASIS frequency after implementation from 16.26% to 4.90% (p<0.001) |
| Episiotomy: Significantly more use of episiotomy after implementation from 13.9% to 21.1% (p<0.001) | |||||||
| Laine et al 20096 | Register study | Finland: Hospital Discharge Register 1987–2007 and Medical Birth Register 2004–2007 Norway: Medical Birth Register, National Public Health Institute Sweden: Medical Birth Register, National Board of Health and Welfare Denmark: Medical Birth Register, National Board of Health | 1968–2007 | All vaginal births in Norway (1968–2007) Sweden (1973–2007) Denmark (1997–2007 Finland (1987–2007) | OASIS: The frequency of OASIS is significantly higher in Denmark (3.6%), Norway (4.1%), and Sweden (4.2%) compared to Finland (0.6%) (p<0.001) The frequency is increasing in all four countries | Episiotomy: Significantly decreasing frequency of episiotomy in all countries (no p value reported) | |
| Hals et al 201014 | Before-and-after study | Tromsø University Hospital, Stavanger University Hospital, Lillehammer Hospital, and Ålesund Hospital, Norway | 40 152 births | 2003–2009 | All vaginal births in 4 obstetric units | OASIS: Significantly lower frequency of OASIS after implementation from 4–5% to 1–2% (p<0.001) | OASIS at instrumental deliveries: Significantly lower frequency of OASIS after implementation from 12.81–16.45% to 6.0–6.7% (p<0.001) |
| Apgar score after 5 min: Improved Apgar score after 5 min (no p value reported) | |||||||
| Blood gas in umbilical cord: No changes | |||||||
| Episiotomy: Significantly more use of episiotomy in 2 units (p<0.001), but unchanged in two. | |||||||
| Laine et al 20128 | Before-and-after study | Oslo University Hospital, Norway | 31 709 births | 2003–2005 and 2008–2010 | All births in one obstetric unit Excluded: Sectio, preterm births (GA <32 weeks), and multiple pregnancies | OASIS: Significantly lower OASIS frequency after implementation from 4.0% to 1.9% (p<0.01) The reduction was seen in all the groups. | OASIS at instrumental deliveries: Reduction in the frequency of OASIS from 10.8% to 5.0% at instrumental deliveries (p<0.01) |
| Episiotomy: Significantly increased use of episiotomy in primiparous women from 31.4% to 36.2% (p<0.001) | |||||||
| Episiotomy at spontaneous deliveries: Significantly decreased use of episiotomy in primiparous women from 24.7% to 22.7% (p=0.006) | |||||||
| Episiotomy at instrumental deliveries: Significantly increased use of episiotomy in primiparous women from 60.8% to 85.1% (p<0.001) | |||||||
| Laine et al 20137 | Register study | Norway: Medical Birth Registry of Norway, National Institute of Public Health Sweden: Medical Birth Register, National Board of Health and Welfare Denmark: Medical Birth Register, National Board of Health Finland: Hospital Discharge Register 1987–2004 and Medical Birth Register 2004–2010 | 574 175 births | 2004–2010 | All vaginal births in Norway (1968–2010), Sweden (1973–2010), Denmark (1997–2010), and Finland (1987–2010) | OASIS: Finland had a lower frequency of OASIS (0.7–1.0%) compared to other Scandinavian countries (2.3–4.2%) (no p value reported) | Episiotomy: Frequency of episiotomy in Norway was increased from 17.8% in 2004 to 19.1% in 2010 (p<0.001) Frequency of episiotomy in Finland was decreased from 32.0% to 24.0% (p<0.001) |
| Stedenfeldt et al 201329 | Before-and-after study | Tromsø University Hospital, Stavanger University Hospital, Lillehammer Hospital, Ålesund Hospital, and Oestfold Hospital Trust, Norway. Same data as Laine et al 2008 28 and Hals et al 2010 14 | 40 154 births | 2003–2009 | All vaginal births in 5 obstetric units in Norway. Excluded: GA< 22 weeks and birth weight < 500 g | OASIS: Significantly reduced risk for OASIS after the intervention (59%; OR: 0.41; 95% CI 0.36 to 0.46). | Apgar score 5 min after birth: Significantly increased frequency of Apgar score <7 (p=0.02) |
| Episiotomy: Significantly increased frequency of episiotomy after the implementation (14.4–24.3%; OR: 1.92; 95% CI 1.82 to 2.02) |
GA, gestational age; OASIS, obstetric anal sphincter injuries.