Abstract
The use of amniotic fluid α-fetoprotein measurements in the early prenatal diagnosis of central nervous system disorders is reviewed. The method is sensitive and specific and has had a pronounced effect on the counselling of mothers who have already had a child with spina bifida or anencephaly. Measurement of other amniotic fluid components, such as fetal macrophages, β-trace protein, α2-macroglobulin or fibrinogen-degradation products, is less reliable and these should not be used in making primary diagnoses. The assay of α-fetoprotein in maternal serum shows signs of being a useful preliminary screening process, and may identify pregnancies where amniocentesis and confirmatory amniotic fluid determinations should be offered.