title: Secular trends in anencephalus prevalence in New Zealand.
abstract: Although the aetiology of anencephalus is unknown, changes in prevalence over time are thought to provide strong evidence of the effect of environmental factors in causation. In a number of countries the rate of this neural tube defect is declining. The rate in New Zealand has also fallen significantly (p less than 0.001) from 1.17/1000 total births in 1968 to 0.39/1000 in 1983, with the greatest decrease occurring in the female rate (approximately 4.16% per year). The aetiological implications of these findings and their consequences for programmes of prenatal diagnostic testing and maternal screening are discussed.
mesh_terms: D000032:Abortion, Therapeutic; D000757:Anencephaly / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D004782:Environmental Health; D005260:Female; D005820:Genetic Testing; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D009520:New Zealand; D011247:Pregnancy; D011296:Prenatal Diagnosis