Warfarin embryopathy (Coumadin embryopathy) is a condition associated with administration of warfarin during pregnancy (1).
Effects of Warfarin in pregnancy
Warfarin (Coumadin) is among oral anticoagulants and acts as an antagonist of vitamin K. Serious bleeding complications may occur both in the fetus (especially into the central nervous system) and in the mother. In addition to bleeding risks, Warfarin has significant teratogenic effects. Warfarin is a low molecular anticoagulant. It crosses the placenta and can cause spontaneous abortion, fetal death before or soon after birth, as well as a wide range of congenital defects. Warfarin inhibits synthesis of clotting factors dependent on vitamin K (II, VII, IX, X).
In 15-40% taking warfarin during pregnancy cause harm to the fetus – warfarin embryopathy. Embryopathy symptoms include: Chondrodysplasia, brachydactyly, microcephaly and eye damage. Warfarin in the first trimester is absolutely contraindicated. The most critical period is between 6 to 9 weeks of gestation. However taking warfarin in the second and third trimesters can be also risky.
Previous studies have shown that central nervous system abnormalities develop due to usage of warfarin in second and third trimester (secondary to bleeding and formation of blood clots in blood vessels). However, the case of using warfarin during the 8 and 12 weeks of pregnancy, which result in abnormalities of central nervous system suggests that warfarin may have a direct teratogenic (harmful) effects on the central nervous system development. Teratogenic effects can occur from exposure to warfarin in the embryonic stage and fetal stage. It is possibly caused secondarily by damage of fetal structures caused by bleeding into organs as a result of a lack of vitamin K, which is caused by warfarin.
Planning for pregnancy in patients with warfarin
A woman who uses a long-term oral anticoagulants should be transferred to heparin before a planned pregnancy. If you become pregnant while taking warfarin it is important to visit your specialist as soon as possible and be transferred from warfarin to low molecular weight heparin. It is also important to undergo a detailed genetic examination and consultation to prevent possible harm to the fetus.