Variability in caesarean section rates for very preterm births at 28-31 weeks of gestation in 10 European regions: results of the MOSAIC project

Objective: Given the continuing debate about the benefits of caesarean section for very preterm infants, we sought to describe caesarean section rates for infants between 28 and 31 weeks of gestation in European regions and their association with regional mortality and short-term morbidity.

Study design: Singletons and twins without lethal congenital anomalies alive at onset of labour from 28 to 31 weeks of gestation from the 2003 MOSAIC cohort of very preterm births in 10 European regions were analysed (N=3,310). Determinants included maternal and fetal characteristics as well as regional caesarean section rates for all births. We explored correlations between caesarean section rates and mortality and morbidity on the regional level.

Results: 95% of infants from pregnancies complicated by hypertension or severe growth restriction detected antenatally were delivered by caesarean section (regional range: 90-100%) versus 55.4% (range: 29-84%) for other pregnancies. Regional caesarean section rates for births at all gestations ranged from 14% to 38% and were correlated with very preterm caesarean rates (p=0.011). Determinants of caesarean section differed between regions with high versus low rates: multiples were more likely to be born by caesarean section in regions with high rates. There were no regional level correlations between caesarean section rates and mortality and morbidity.

Conclusions: With the exception of pregnancies with hypertension and growth restriction, there was broad variation in very preterm caesarean section rates between regions after adjustment for clinical factors. Given maternal risks associated with caesarean section, more research on its optimal use for very preterm deliveries is necessary.