Use of low molecular weight heparin for prophylaxis and treatment of thromboembolism in pregnancy.

Low molecular weight heparin (LMWH) preserves the antithrombotic action but not the anticoagulant activity of heparin. LMWH is safe, does not cross the placenta and is administered as a single daily injection. We report our experience with 6 pregnant women given LMWH for treatment or prophylaxis of thromboembolism. The drug was successfully given to 5 women for periods of 6 weeks--6 months and no thromboembolic complications occurred during pregnancy or pueperium. There were no hemorrhagic complications and no excessive bleeding was observed during delivery. The sixth patient relapsed after 6 weeks of therapy. This patient also showed resistance to standard heparin administered intravenously at a very high dose. LMWH should be considered an alternative to standard heparin in pregnant women requiring antithrombotic prophylaxis and therapy.