Hemodynamic effects of prostaglandin E1 on lambs in utero.

Fetal tissues and the uteroplacental circulation are known to be exquisitely sensitive to the prostaglandins. E-series prostaglandins cause generalized vasodilatation in mature animals. This phenomenon is observed in the fetus but its effects are markedly obscured by the decrease in umbilical-placental flow. Comparison to hemodynamic data in hypoxemic fetuses clearly demonstrates that these effects are both qualitatively and quantitatively different, and therefore are likely to be due either to the direct effect of the drug, or to reflexes elicited by the marked compromise of the umbilical-placental flow.