Blood platelet behaviour in mothers and neonates.

Blood platelet behaviour was compared in mothers at birth and their babies, and in non-pregnant, female controls. Platelet responses to arachidonic acid (AA) and to adrenaline were measured in platelet-rich plasma and the inhibitory effects of prostacyclin (PGI2) were determined. Platelets from the mothers differed from those from the neonates and controls in that lower concentrations of AA were needed to induce platelet aggregation and a release reaction. In addition, more PGI2 was needed to inhibit AA-induced platelet aggregation. Platelets from the neonates differed from the mothers and controls in that they were almost completely insensitive to adrenaline. They did not differ from the controls in their sensitivity to AA or PGI2 but the extent of the release reaction induced by AA was significantly reduced.