Participants
At Innlandet Hospital Trust, Lillehammer, Norway, detailed information
on maternal health, pregnancy, delivery and the postpartum period until
discharge is prospectively registered in a perinatal database. This
hospital covers virtually all births in a region with a population of
around 90,000 people at the time of the study; around 23,000 lived in
the city Lillehammer and the others in rural areas with small towns. The
women were generally first registered in the perinatal database at 18-20
weeks’ gestation when they met for the routine ultrasound assessment.
This study included all deliveries that occurred during January
1st 1990 to December 31st 2002. We
identified singleton vaginal deliveries with gestational age
>210 days where women for the first time were diagnosed
with perineal rupture from the database, and the data were quality
assured and expanded by scrutinizing delivery protocols, charts, and
patient records. Women with 3rd and
4th degree OASI were defined as cases, and we selected
the next vaginal singleton delivery with the same parity and gestational
age >210 days without OASI as a matched control.