Thromboxane dominance and prostacyclin deficiency in habitual abortion.

To evaluate the significance of vasoactive prostanoids in habitual abortion, we measured urinary excretion of prostacyclin metabolites (6-keto-PGF1 alpha and 2,3-dinor-6-keto-PGF1 alpha) and of thromboxane A2 metabolites (TxB2 and 2,3-dinor-TxB2) during 25 pregnancies in 22 women with recurrent spontaneous abortion (RSA). The control group were 16 pregnant women with no history of abortion. Ultrasound examination at first follow-up appointment showed a living fetus in 23 pregnancies of women with RSA. 9 of these pregnancies ended in abortion; 14 continued to term as did all the pregnancies in the control group. Compared with controls, women with RSA had a lower (p less than 0.05) ratio of prostacyclin to thromboxane between weeks 4 and 7 of gestation and a lower (p less than 0.01) output of 2,3-dinor-6-keto-PGF1 alpha between weeks 8 and 11. Women whose pregnancies ended in abortion had higher (p less than 0.05) output of 2,3-dinor-TxB2 between weeks 4 and 7 of gestation and lower (p less than 0.01) excretion of 2,3-dinor-6-keto-PGF1 alpha between weeks 8 and 11 compared with women whose pregnancies proceeded to term. We conclude that deficiency of vasodilatory prostacyclin may be a factor in habitual abortion.