Neonatal platelet reactivity and serum thromboxane B2 production in whole blood: the effect of maternal low dose aspirin

Abstract

Objectives: Concern has been expressed about possible neonatal side effects after the use of maternal anti-platelet agents in pregnancy, particularly low dose aspirin treatment. We have studied neonatal platelet behaviour using whole blood techniques, and assessed the neonatal effect of the maternal ingestion of 60 mg aspirin daily.

Design: Cross sectional and randomised, double-blind, placebo-controlled.

Setting: University hospital.

Subjects: 1. Eight normal women, studied before conception, and their infants. 2. Twenty-four infants whose mothers had been randomised to receive either 60 mg aspirin daily, or placebo, in double-blind fashion.

Methods: The Clay Adams Ultra Flo 100 whole blood single platelet counter was employed to measure platelet aggregation in response to various agonists. The platelet release reaction was also measured in whole blood, and serum thromboxane B2 (TxB2) production was measured by radio-immunoassay. Umbilical cord blood samples were obtained at delivery.

Results: 1. Neonatal platelet aggregation induced by adrenaline, ADP and platelet activating factor was reduced in comparison with their mothers (P < 0.01), whereas the neonatal platelet release reaction was reduced when stimulated by collagen and U46619 (a thromboxane mimetic) (P < 0.01). Serum TxB2 production was similar in mothers and babies. 2. Neonatal platelet aggregation, release reaction and serum TxB2 production were not significantly reduced in infants exposed to maternal aspirin in comparison with those neonates exposed to maternal placebo. This is in contrast to the effect on maternal platelets.

Conclusions: Although only a small number of patients were studied, we interpret this as a relative sparing of neonatal platelet reactivity due to the presystemic action of low dose aspirin.