[Surgical delivery in Norway during the last 20 years--analysis of great changes].

In Norway, the frequency of deliveries by cesarean section rose from 2.0% to 12.6% between 1968 and 1990. During the same period vaginal births of foetuses in breech presentation decreased by about 50%. All types of operative delivery were more common among women giving birth for the first time than among those who had given birth previously. Throughout the twenty years of our study the highest frequency of operative delivery was found in the health region comprising Oslo and the counties of Hedmark and Oppland in the eastern part of Norway. But the difference in relation to the other regions diminished toward the end of the 1980s. When university clinics were compared with non-university departments, we found that the frequencies were 2.0 to 2.5 percentage points higher at the former throughout the study period, again with a tendency toward less difference in the most recent years. With few exceptions, the frequency of cesarean section was positively correlated to the annual number of births in the departments. Already in 1970-71 cesarean section was performed on more than one fourth of the para 0 mothers aged 35 and above. This frequency rose to 40% in 1984-86, and then dropped to 35% in 1989-90. The most striking trend in cesarean section practice was noted for low birth weight, with a dramatic increase for birth weights below 2,500 g. While birth weight-specific cesarean section rates differed little along the weight scale in 1970-71, in the years 1989-90, 67% of the births weighing between 1,000 and 1,499 g in 1989-90 were delivered by cesarean section.