For women who have had unexplained recurrent miscarriages, treatment with aspirin or another blood-thinner to prevent blood clots seems to improve their chances of delivering a live infant, researchers in Israel report.

The formation of blood clots, or thrombosis, is believed to be one possible cause of recurrent miscarriage, they explain in the medical journal Fertility and Sterility, but it is unclear whether prevention of thrombosis can increase live birth rates.

To investigate, Dr. Mordechai Dolitzky from Sheba Medical Center, Tel Hashomer, and colleagues compared the effect of preventing blood clots with aspirin or enoxaparin - a form of heparin - in 104 pregnant women with a history of unexplained recurrent miscarriages.

The live birth rate was over 81 percent in both groups, the researchers report. They say this rate exceeds the expected live birth rate of 40 percent to 60 percent among women with recurrent miscarriages.

Five women in each group had preterm deliveries and neonatal complications were somewhat more common in the aspirin group.

“Both treatment regimens were associated with a good pregnancy outcome in terms of live births and late pregnancy complications,” Dolitzky and his colleagues conclude.

“In view of the minimal risks of enoxaparin and aspirin to the mother and fetus,” they recommend that “either form of treatment should be considered in women after three or more pregnancy losses.”

SOURCE: Fertility and Sterility, August 2006.