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Changes in prognosis of twin births over 20 years.

The study is based on two birth cohorts from the years 1966 and 1985-1986. Perinatal mortality of twins has fallen over 20 years from 9.2% to 3.1%. Improvement is particularly remarkable in neonatal mortality (less than 28 days) of preterm (less than 34 gestational weeks) twins, from 47.4% to 8.6%, whereas the incidence of stillbirths has not fallen greatly. The proportion of preterm births has not fallen significantly, 48.4% vs. 38.1%. Many factors, considered favourable to the course and outcome of pregnancy have improved simultaneously: women are taller, less overweight, and more educated; pregnancies are wanted and sick and maternity leave provisions have improved. The follow-up of twin pregnancies and deliveries has been centralized and is more effective. In particular, neonatal care is also better than 20 years ago. The prognosis of twins has improved in parallel with the singletons, but the perinatal mortality is still approximately four time and the incidence of prematurity ten times more than in singletons.