To compare rates of preterm birth among multiple births in European countries, to estimate their contribution to overall preterm birth rates and to explore factors which could explain differences between preterm birth rates.Design
Analyses of data from vital statistics, birth registers or national samples of births.Setting
Eleven member states of the European Union.Population
All live births or representative samples of births at national or regional level for the year 2000 or most recent year.Methods
Description of rates of preterm birth before 37 and 32 weeks, estimation of population attributable risks (PAR), study of associations between preterm birth rates in multiples and singletons and nonspontaneous labour using Spearman's rank correlation coefficient.Main outcome measures
Preterm birth rates, PAR, proportions of deliveries with nonspontaneous onset (caesarean sections before labour or induction of labour).Results
The proportion of multiple births before 37 weeks varied from 68.4% in Austria to 42.2% in the Republic of Ireland. In half of the countries, over 20% of all preterm births were attributable to multiple births. A strong association was found between the proportions of births before 37 weeks among multiple and singleton births (r= 0.81; P < 0.001). An association was observed between the rates of preterm birth and the proportions of deliveries with nonspontaneous onset among twins.Conclusions
Wide variations in rates of preterm births and deliveries with nonspontaneous onset were found between countries, suggesting marked differences in clinical practice which could have long-term implications for the health of children from multiple births.