title: The declines in dizygotic twinning rates and in birth rates.
abstract: It is suggested that, contrary to Elwood (1973), the current secular decline in age-specific dizygotic twinning rates is not due to the current decline in birth rates except to a minor extent.
authors.affiliation: Galton Laboratory, University College, London.
authors.forename: W H
authors.initials: WH
authors.lastname: James
mesh_terms: D000328:Adult; D001723:Birth Rate / Q000639:trends*; D005260:Female; D005298:Fertility; D006801:Humans; D007231:Infant, Newborn; D014429:Twins, Dizygotic; D006113:United Kingdom / Q000453:epidemiology