Abstract
Background. A European multicenter study (Surveillance of Cerebral Palsy in Europe, SCPE) was used to describe changes over time in multiple birth rates and cerebral palsy (CP) rates among multiple born infants, to compare CP rates and clinical types between multiples and singletons, and to analyse the influence of birth order in twins. Methods. Data were collected from 12 European population-based CP registers on 6613 children born in 1975-90, as well as demographic data. Results. The rate of multiple birth in the populations increased from 1.9% in 1980 to 2.4% in 1990, and the proportion of multiples among CP infants increased from 4.6% in 1976 to 10% in 1990. Multiples have a four times higher rate of CP than singletons [7.6 vs. 1.8 per 1000 live births, relative risk (RR) 4.36; 95% confidence interval (CI) 3.76-4.97] overall. The risk is marginally higher in multiples with birthweight > 2500 g (RR 1.60; 95% CI 0.95-2.28) and born at term (RR 1.65; 95% CI 0.91-2.40), and there is no difference in the risk for the low-birthweight and preterm groups. Correcting for differences in gestational age and birthweight, the clinical type of CP was the same in multiples and singletons. Twin CP infants are more often second than first born (56% vs. 44%, p < 0.05). Conclusions. Multiple born infants have a four times higher risk of developing cerebral palsy than singletons, mainly related to the higher risk of preterm birth in multiples. As the rate of multiples doubled through the 1980s, cerebral palsy cases in multiples increased in the same period.