Trends in caesarean section rates among high- and medium-risk pregnancies in The Netherlands 1983-1992.

During the last two decades, the rates of operative deliveries have been rising constantly in all industrialized countries including the Netherlands. Within the framework of the project 'Obstetric Peer Review' (Verloskundige Onderlinge Kwaliteitsspiegeling), the trends in the caesarean section rates were investigated, using the data of the Perinatal Database of the Netherlands (LVR), but only among the high- and medium-risk pregnancies. To that end homogeneous high-risk subgroups, with respect to pregnancy- or delivery-related complications, were defined in various ways and caesarean section rates were calculated for these groups. Irrespective of the definition of such a group (e.g. multiple pregnancy or breech presentation), an increase of the caesarean section rates evidently emerges. The rates of planned caesarean section appear to increase more than the rates of emergency caesarean section. The increase for the multiparae is greater than for the primiparae. It is striking that the largest increase was found within the medium-risk group (namely; singletons, at term, vertex presentation, normal birthweight, mothers aged 20-35 years and with a normal diastolic blood pressure). Although no evident pathology can be found in the data, these women do not belong to the low-risk group, because they were referred to an obstetrician. For the multiparae in this group, the risk of a planned caesarean section yearly increased by a factor 1.09 (i.e. 9%).