However, the disadvantage of high dose steroids soon became evident. In addition, the steroids made the pregnant woman susceptible to infection by bacteria that could affect the mother, but, just as importantly, may kill the baby, such as listeriosis. Lose dose aspirin 75 mg daily works by preserving prostacyclin synthesis from platelets, providing unsticky platelets and opening of the vessels, while inhibiting thromboxane synthesis, which tends to make platelets stick together and blood vessels constrict and narrow, promoting thrombosis. It is these patients who benefit from the combination of low dose aspirin and a new product called low molecular weight heparin which is safe in pregnancy. This is given as a daily injection under the skin.
Heparin works by direct effect on the coagulation cascade and provides good anticoagulation.
Further research is always needed and, at the present time, a multicentre trial, comparing aspirin versus aspirin and heparin in pregnancy, is underway and, hopefully, the results will be ready by the end of next year.