Low-dose aspirin in prevention of miscarriage in women with unexplained or autoimmune related recurrent miscarriage: effect on prostacyclin and thromboxane A(2) production

Early pregnancies in women with a history of recurrent spontaneous abortion (RSA) are accompanied by a deficiency in vasodilatory and anti-aggregatory prostacyclin (PGI(2)) and/or overproduction of its endogenous antagonist thromboxane A(2) (TXA(2)), We evaluated the effect of a low-dose aspirin (LDA) on PGI(2) and TXA(2) production and on pregnancy outcome in RSA women with and without detectable anticardiolipin antibodies (ACA), Of 82 RSA women studied, 66 became pregnant, and of them, 33 (six with elevated and 27 with normal ACA concentrations) were randomized to receive LDA (50 mg/day) and 33 (six with elevated and 27 with normal ACA concentrations) to receive placebo (PLA) from a mean of 6.6 days after the missed period to delivery, Treatment with LDA inhibited platelet TXA(2) production similarly in RSA women with and without detectable ACA and with continuing pregnancies (7.0 +/- 0.7 ng/ml, LDA group versus 254.5 +/- 37.8 ng/ml, PLA group, mean +/- SEM, P < 0.0001) or miscarrying pregnancies (13.8 +/- 3.8 ng/ml compared with 233.6 +/- 59.8 ng/ml, P < 0.0001 respectively), Furthermore, LDA decreased urinary excretion of the TXA(2) metabolite (2,3-dinor-TXB2) both in pregnancies which went to term (6.1 +/- 0.6 ng/mmol creatinine, LDA group versus 19.3 +/- 3.0 ng/mmol creatinine, PLA group, P < 0.0001) or again ended in miscarriage (4.7 +/- 0.8 ng/mmol creatinine versus 17.3 +/- 4.4 ng/mmol creatinine, P < 0.0001 respectively), but did not affect the excretion of the prostacyclin metabolite (2,3-dinor-6-keto-PGF(1 alpha)). Early pregnancy ultrasound examination revealed a living fetus in 58 women, Of these, seven in the LDA group (23.3%, four with elevated and three with normal ACA concentrations) and five in the PLA group (17.9%, two with elevated and three with normal ACA concentrations; not significant) experienced a miscarriage, All infants were healthy, and the frequency of growth retardation was similar in both groups (13.0%), One woman in the LDA group (4.3%) and three women receiving PLA (13.0%) developed pre-eclampsia (not significant), Therefore, although treatment with LDA caused a desirable biochemical effect, it did not improve pregnancy outcome in RSA women with or without detectable ACA.