Distribution of alpha 1-fetoprotein in fetal plasma, allantoic fluid, amniotic fluid and maternal plasma of cows.

Maximal concentrations of AFP, measured by RIA, were obtained in fetal plasma and amniotic and allantoic fluid between the 3rd and 4th month of gestation, with levels declining thereafter until term. AFP values in maternal plasma were unchanged. Throughout gestation, AFP values were higher in allantoic than in amniotic fluid and the ratio of allantoic fluid/amniotic fluid AFP was significantly correlated with gestational age.