Alpha-fetoprotein in amniotic fluid and serum from pregnant women with severe rhesus isoimmunization.

In 12 pregnant women with severe rhesusiso-immunization the AFP concentration in amniotic fluid (50 samples), maternal serum (212 samples) and cord blood (5 samples) were determined by immuno-electrophoresis. With surviving infants (9 patients) the initial values in amniotic fluid before intrauterine transfusion (IUT) lie evenly distributed within the 90% reference interval. In serum the initial values are within the 90% reference interval, but above the mean level for AFP concentration for gestational age. A similar pattern is seen in the period up to delivery. In 3 cases of intrauterine/neonatal death the initial concentrations of AFP in maternal serum were significantly above the upper limit of normal range, whereas all the initial amniotic fluid concentrations were close to 95% fractile. Intrauterine transfusions do not influence the AFP profiles in a uniform way. The AFP concentration in maternal serum may be used in evaluation of severe rhesus-isoimmunized pregnancies.