DECREASING INCIDENCE OF SPINA BIFIDA AND ANENCEPHALY
The notification of congenital malformations in England and Wales is voluntary, and from time to time some malformations become foci of attention because, for example, a preventive programme shows promises of success, surgeons begin to offer a treatment not previously available, or diagnosis improves. The notification rate was 220.8 per 10,000 in total births in 1983, almost 5% up on the previous year and the highest in the decade 1974 to 1983. The cause may be disputed but there is no doubting the decline in incidence of spina bifida, down to 6.7 per 10,000 last year from 18.3 in 1974, while the rate for anencephalus fell from 13.1 to 1.8 per 10,000 over the decade. Age-specific rates for individual malformations year by year are not provided but an impact of screening for Down syndrome is not discernible. The U-shaped graph of maternal age against malformation rate is defied by Down syndrome and the rate for women aged 45 or more is ten times that for women aged 30-34—but there were only 7 Down syndrome births in the oldest groups compared with 130 in the younger women. A preventive programme restricted to but 100% effective in women aged 35 or more would have prevented the births of only 27% of Down syndrome babies.
