To evaluate the amount of antenatal care days in level III hospitals caused by regionalization of very preterm deliveries.
We included all 171,997 pregnancies registered in Finland between January 1, 2004 and December 31, 2006. Data on deliveries from the Medical Birth Register were linked to the Hospital Discharge Register. Maternal zip codes were used to define whether a mother lived inside or outside a level III hospital region. Regionalization was defined as care in level III hospitals between gestational weeks 22 and 32 among mothers living outside level III hospital regions. Pregnancies were divided into 3 groups based on the gestational age at delivery: very preterm (