Data relating to the incidence of anencephalus for the 12-year period 1961-72 were abstracted from the Statistical Reviews of the Registrar General for Scotland. It was shown that considerable geographical variation is still apparent with the highlands having, in general, the lower incidences. In comparison with the earlier study of Edwards (1958), there were some changes: the incidence in the ...

The hypothesis proposed by Knox (1970) that an anencephalic fetus arises from a fetus-fetus interaction between two dizygous twins predicts that the twinning rate, the population incidence of anencephalus, and the female proportion of anencephalics in a population should be positively interrelated. These associations were tested using Canadian data during a long period of time and over a large ...

A study has been made of the sexes of the affected within sibships containing two or more members with anencephaly or spina bifida (ASB). There is no clear evidence for variation between ASB-prone women in their propensity to bear affected cases of one sex rather than the other. It is suggested that the point should be regarded as open until further data have settled the issue.