Comparison of alphafetoprotein and beta-trace protein in the antenatal diagnosis of anencephaly and spina bifida.

Alphafetoprotein (AFP) and beta-trace protein (BTP) concentrations have been measured in amniotic fluids taken from 19 pregnancies where the outcome was an infant with a neural tube defect and from 19 matched controls. There was no significant difference in the mean BTP values for the pathological samples when compared with the controls, and there were no striking differences in the values within individual matched pairs. On the other hand, the mean AFP concentration in the abnormal amniotic fluids was approximately 15 times the mean value found in the controls. Differences within individual pairs were particularly noticeable early in pregnancy. It is concluded that BTP is of no use for the early antenatal diagnosis of anencephaly and spina bifida.