Alpha fetoprotein levels in maternal serum and in amniotic fluid from early normal pregnancies

Alpha fetoprotein (AFP) was determined in serum from 241 women in the 8th to 43rd week of gestation by quantitative radioimmunoelectrophoresis, and in 103 amniotic fluid samples from the first half of pregnancy by rocket immunoelectrophoresis. Both serum and amniotic fluid samples were obtained from a larger material, but samples were included only from pregnant women whose infants were normal at birth. The 90% normal AFP range was calculated both for maternal serum and for amniotic fluid.