The significance of alpha-feto-protein (AFP) and human chorionic gonadotrophin (HCG) during the first half of pregnancy (author's transl)

Abstract

The determination of AFP and HCG was used as a diagnostic parameter for the functional integrity of the feto-placental unit during the first 20 weeks of normal and disturbed pregnancies. In contrast to HCG which can already be detected very shortly after nidation and reaches a maximum between the 10th and 12th week of gestation, AFP does not begin to rise discernibly before the 8th and 9th week and attains the highest values in the third trimester. The assay of AFP did not contribute relevant data when carried out before the 10th week of pregnancy. Contrary to that, an irreversibly damaged pregnancy has to be expected when lower than normal AFP values are found after the 10th week, even in the presence of a normal level of HCG. Likewise, higher than normal values should be taken as a reliable sign of embryonal demise after the 14th week of pregnancy, as long as a multiple gestation, a previous amniocentesis or a neural tube defect can be excluded. Serum AFP did not only increase markedly in many cases after interruption of pregnancy, but even after amniocentesis or premature rupture of the amniotic sac when fetal cells having a high content of AFP enter the maternal circulation.