To examine whether the introduction of advanced diagnostic technology in maternity care has led to less variation in type of delivery between hospitals in Norway.
The Medical Birth Registry of Norway provided detailed medical information for 1.7 million deliveries from 1967 to 2005. Information about diagnostic technology was collected directly from the maternity units.
The data were analyzed using a two‐level binary logistic model with Caesarean section as the outcome measure. Level one contained variables that characterized the health status of the mother and child. Hospitals are level two. A heterogeneous variance structure was specified for the hospital level, where the error variance was allowed to vary according to the following types of diagnostic technology: two‐dimensional ultrasound, cardiotocography, waveform analysis, and fetal blood analyses.
There was a marked variation in Caesarean section rates between hospitals up to 1973. After this the variation diminished markedly. This was due to the introduction of ultrasound and cardiotocography.
Diagnostic technology reduced clinical uncertainty about the diagnosis of risk factors of the mother and child during delivery, and variation in type of delivery between hospitals was reduced accordingly. The results support the practice style hypothesis.