Alpha-fetoprotein content of amniotic fluid in normal and abnormal pregnancies.

Elevation above the normal range of alpha-fetoprotein (AFP) concentration in amniotic fluid occurs in the presence of certain fetal anomalies. The value of a new method for radioimmunoassay of APF in amniotic fluid was tested by an analysis of 486 samples taken by amniocentesis at various stages of pregnancy. The normal range of concentrations during pregnancy was established by 348 samples from healthy women with normal pregnancies. This was compared with the levels found in the presence of various fetal malformations--Rh-isoimmunization, maternal diabetes, chromosomal anomalies, and fetal death in utero. The findings and their implications are discussed.