Prolactin-releasing system in maternal, fetal, and amniotic compartments during labor.

The effect of a dopamine antagonist on prolactin concentrations was studied in maternal, fetal plasma, and amniotic fluid in term gestation. Twenty-three women with normal full-term pregnancies received 10 mg metoclopramide intravenously during labor. The prolactin levels in maternal plasma increased significantly after metoclopramide. However, the prolactin levels in amniotic fluid and fetal plasma did not change significantly after administration of this drug. Although the increased values of prolactin in maternal plasma were significantly correlated with metoclopramide concentrations after metoclopramide injection, there was no correlation between these two values in amniotic fluid. The authors conclude that the prolactin-releasing system in amniotic fluid is independent of the maternal hypothalamopituitary axis.