Monitoring the effects and managing the side effects of anticoagulation during pregnancy

Anticoagulant therapy is given to pregnant women for the treatment or prevention of venous thromboembolism (VTE) and for secondary prevention of some adverse pregnancy outcomes in case of biological predisposition. Anticoagulation is also used for the prevention of systemic embolism in women with mechanical heart valves. Vitamin K antagonists cross the placenta, are teratogenic when given up to the sixth week of gestation, may induce embryopathy and central nervous system abnormalities, and should be avoided during the weeks preceding delivery due to potential bleeding complications. Low-molecular-weight heparins, which seem to be safe and effective for the prevention or treatment of VTE in pregnancy, have replaced unfractionated heparins in women who have normal renal function. Their monitoring, when indicated, is based on antifactor Xa plasma activity. Their main complications are bleeding, skin allergic reactions, heparin-induced thrombocytopenia, and osteoporosis.