A descriptive evaluation of unfractionated heparin use during pregnancy

The mainstay of oral anticoagulant therapy, warfarin sodium, crosses the placenta during pregnancy and may cause fetal complications. Unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) do not cross the placenta and have demonstrated utility in the prevention and treatment of thrombosis during pregnancy.

The purpose of this study was to review treatment strategy, indication, and maternal and fetal outcomes in anticoagulated pregnancies at Kaiser Permanente Colorado.

We identified 103 pregnancies in 93 mothers prescribed an anticoagulant during a pregnancy occurring between January 1, 1998 and March 31, 2005.

The majority of patients were treated with UFH (89.3%). Indications for anticoagulation included venous thromboembolism (VTE) prophylaxis (53.4%), history of pregnancy loss (29.1%), acute VTE (16.5%), and history of cerebral vascular accident (CVA) (1.0%). There were no maternal deaths. Fetal demise occurred in 8 pregnancies (7.8%) at a median 14 weeks gestation (range 7-22 weeks). No fetal demise occurred in pregnancies treated for acute VTE or history of CVA. There were two occurrences of pulmonary embolism (1.9%) and two hemorrhagic events requiring transfusion (1.9%).

Maternal and fetal adverse events were infrequent in our population of anticoagulated pregnancies. UFH remains a viable option among more expensive LMWH products.