The prevention of Down's syndrome in the south western region of England 1975-1985.

Cytogenetic prenatal screening for Down's syndrome in the South West Region of England from 1975 to 1985 was reviewed. The use of amniocentesis increased, and for the years 1981 to 1985 averaged 29.4% of women 35 years or over at their estimated date of delivery. 58 pregnancies were terminated after karyotyping of amniotic fluid cells confirmed trisomy 21. 385,440 live births were born in the region, 452 with Down's syndrome, giving a live birth incidence of 1 in 853. The effective impact of prenatal screening was calculated at an overall 8.3% reduction in Down's syndrome live births, but for the years 1981 to 1985 this rose to 11.3%. In spite of the introduction of new prenatal screening programmes that are not reliant solely on maternal age, it is predicted that substantial numbers of children with Down's syndrome are likely to be born each year. Adequate medical facilities will still be required for the survivors.