Prevalence of neural tube defects in 16 regions of Europe, 1980-1983. The EUROCAT Working Group.

A total of 1633 cases of neural tube defects were analysed, registered between 1980 and 1983 in liveborn and stillborn babies and in fetuses aborted as a result of prenatal diagnosis of malformation in 16 EUROCAT Registries (total births = 766,603). A clear geographical pattern was observed. The highest neural tube defect (NTD) rates were seen in Dublin (Ireland), Belfast (UK) and Glasgow (UK) with 40 cases per 10,000 births and in these centres there was a significant decrease in prevalence over the years. In Galway (Ireland) and Liverpool (UK), the rates were approximately 20 cases per 10,000 births, the rate decreasing over years in Liverpool. In the registries situated in continental Europe, the prevalence varied between 6 and 13 cases per 10,000 births and there was no apparent change in the prevalence with time. The spina bifida/anencephaly ratio and the male proportion among the NTD cases were both lower in the British Isles than in continental Europe. Cases of prenatal diagnosis of NTD resulting in termination of pregnancy formed 19% of the total NTD cases, this proportion increasing over years. A large variation between centres was seen in the effectiveness of prenatal screening for NTD.