Venous thromboembolism in pregnancy.

Low molecular weight heparins (LMWHs) appear to be as safe and effective as unfractionated heparin (UFH) for venous thromboembolic disease (VTED) treatment or prophylaxis during pregnancy. Experience with other parenteral anticoagulant drugs is very limited, and no alternative oral anticoagulants are available to date. In addition to cost, challenges of long-term LMWH use during pregnancy that have not been addressed by controlled clinical trials include a) ideal dosing as pregnancy advances, b) the need for LMWH monitoring by anti-Xa activity levels, and c) ideal therapeutic management as the delivery date nears. Because therapeutic-intensity anticoagulation during pregnancy is challenging, many practitioners favor a more "aggressive" approach toward VTED prophylaxis in women perceived to be at very high risk of thrombosis during pregnancy. Best evidence to date suggests that most women with thrombophilias or with a previous "situational" VTED event probably do not require VTED prophylaxis antepartum, but postpartum anticoagulation prophylaxis is recommended for a few weeks. For those with a history of previous idiopathic VTED or VTED associated with "hormonal challenge" (such as with contraceptive use or previous pregnancy), prophylaxis beginning antepartum may be considered and discussed with the patient. Selected cases of "severe" thrombophilia are probably best managed by initiation of pharmacologic VTED prophylaxis antepartum. However, it must be emphasized that data from prospective controlled clinical trials are lacking.