Prostacyclin concentrations in cord blood and in the newborn

The levels of 6-oxo-prostaglandin F1 alpha (6-oxo-PGF1 alpha) were measured in cord blood and in peripheral venous blood in newborns using gas chromatography coupled with negative ion chemical ionization mass spectrometry. The plasma concentrations of 6-oxo-PGF1 alpha in cord blood increased significantly between delivery and placental expulsion (P less than .005). In newborns, the circulation levels of 6-oxo-PGF1 alpha after four hours of life were low and comparable to adult levels. Large quantities of prostacyclin are produced by the uteroplacental unit during parturition, but only small amounts are transmitted to the newborn during a normal delivery. The low plasma concentrations of 6-oxo-PGF1 alpha in newborns suggest that prostaglandin I1 is not a circulating vasodilator during the first week of life.