Alpha-fetoprotein levels in amniotic fluids from spontaneous abortions.

Alpha-fetoprotein (A.F.P.) levels in the amniotic fluid were determined in 54 cases of spontaneous abortion in which the amniotic sac remained intact. These levels were correlated with the morphological and cytogenetic status of the fetus. Of the 29 fetuses with no apparent abnormality 22 had A.F.P. levels below 50 mug/ml, while 10 of the 11 fetuses with severe neural tube defects had raised levels (50-305 mu/ml). Seventeen fetuses had chromosome anomalies of various types. Three out of four which were 45, X had considerably raised A.F.P. levels (78-210 mug/ml) but fetuses with other chromosome constitutions and no neural tube defects had levels no higher than 32 mug/ml.