Anencephalus, spina bifida, and hydrocephalus incidence related to sex, race, and season of birth, and incidence in siblings.

For the congenital malformations, as for many other non-communicable diseases and defects, the collection of epidemiological knowledge based on statistical procedures is just beginning. A comprehensive investigation of the incidence of malformations of the central nervous system in Birmingham, England, and the relationship of these malformations to certain epidemiological variables, has recently been reported by Record and McKeown (1949; 1950a,b; 1951) and McKeown and Record (1951). With the object of determining the applicability of these authors' results to areas other than England and Wales, a somewhat similar, retrospective investigation was undertaken in Rhode Island, U.S.A. This communication describes the findings of this investigation, with the exception of data relevant to the association with maternal age and parity, which is reported separately (Ingalls, Pugh, and MacMahon, 1953).