Relationship of maternal, fetal, and amniotic fluid prolactin levels

Serum prolactin (PRL) was measured by radioimmunoassay in 80 women in serum and amniotic fluid during various stages of normal pregnancy and at delivery. In addition, prolactin levels were measured in cord sera at 60 newborns. PRL levels in maternal serum progressively increased during pregnancy, and they were lower than the corresponding levels in amniotic fluid. A relative decline in the amniotic fluid prolactin between the 39th and the 40th week of gestation was observed. The mean concentration of PRL in umbilical blood was significant lower than that in maternal blood at delivery. The lack of correlation between the PRL in amniotic fluid and the levels found in maternal and newborns serum suggests an independient source of PRL in each of the three compartments.