Area differences in the incidence of neural tube defect and the rate of spontaneous abortion.

In an attempt to corroborate the finding of Roberts and Lloyd (1973) of increased incidence of previous abortions in women living in those areas of South Wales with relatively low incidences of malformations of the central nervous system, we examined the data of the 1958 British Perinatal Mortality Survey. We also found evidence that the history of preceding abortion among all mothers in this survey was slightly more prevalent in areas where the rates of stillbirth and neonatal death from anencephalus or spina bifida were low, but the order of magnitude was much less than in the Welsh study.