Pregnancy can increase the risk factor for clotting that in abnormal. During pregnancy, thrombophilia can further increase the risk for certain complications from clotting problems. Each pregnant woman is theorized to have a four times higher risk of an abnormal clot when compared to woman who are not pregnant. It is also believed that thrombophilia can increase the risk of blood clots in the placenta or afterbirth. The placenta is where nutrients as well as oxygen are exchanged between the baby and mother. Any clots could block the flow of substances as well as other complications. Anticoagulants are used to lower the ability of the blood to clot. They do not dissolve already existing clots but that normally happens over time. The 2 more common anti-coagulants are Heparin. Warfarin. Heparin is usually administered by injection or thru IVF. It works quickly, so is often the 1st anti-coagulant used.