NEONATAL PLATELET REACTIVITY AND SERUM THROMBOXANE B-2 PRODUCTION IN WHOLE-BLOOD - THE EFFECT OF MATERNAL LOW-DOSE ASPIRIN

Objectives Concern has been expressed about possible neonatal side eff ects after the use of maternal anti-platelet agents in pregnancy, part icularly low dose aspirin treatment. We have studied neonatal platelet behaviour using whole blood techniques, and assessed the neonatal eff ect of the maternal ingestion of 60 mg aspirin daily. Design Cross sec tional and randomised, double-blind, placebo-controlled. Setting Unive rsity hospital. Subjects 1. Eight normal women, studied before concept ion, and their infants. 2. Twenty-four infants whose mothers had been randomised to receive either 60 mg aspirin daily, or placebo, in doubl e-blind fashion. Methods The Clay Adams Ultra Flo 100 whole blood sing le platelet counter was employed to measure platelet aggregation in re sponse to Various agonists. The platelet release reaction was also mea sured in whole blood, and serum thromboxane B-2 (TxB(2)) production wa s measured by radio-immunoassay. Umbilical cord blood samples were obt ained at delivery. Results 1. Neonatal platelet aggregation induced by adrenaline, ADP and platelet activating factor was reduced in compari son with their mothers (P < 0.01), whereas the neonatal platelet relea se reaction was reduced when stimulated by collagen and U46619 (a thro mboxane mimetic) (P < 0.01). Serum TxB(2) production was similar in mo thers and babies. 2. Neonatal platelet aggregation, release reaction a nd serum TxB(2) production were not significantly reduced in infants e xposed to maternal aspirin in comparison with those neonates exposed t o maternal placebo. This is in contrast to the effect on maternal plat elets. Conclusions Although only a small number of patients were studi ed, we interpret this as a relative sparing of neonatal platelet react ivity due to the presystemic action of low dose aspirin.