Venous thromboembolism in pregnancy: prophylaxis and treatment with low molecular weight heparin

Objective. To evaluate the safety of individually dosed low molecular weight heparin (LMWH) for prophylaxis and treatment of thromboembolic complications in pregnancy. Design. Cohort study with a chronologic register-based control group. Setting. Department of Obstetrics and Gynecology, Hiller circle divide d Hospital, Denmark. Population. All 166 women treated with LMWH in pregnancy between 1 January 2001 and 31 December 2005. Methods. Women treated with LMWH in pregnancy were identified and individual case records reviewed retrospectively. General data on the LMWH-treated women were compared to the 18,020 untreated pregnancies within the same period and with 306 matched controls as regards to postpartum hemorrhage (PPH). Main outcome measures. Side effects of treatment, thromboembolic manifestations, postpartum bleeding and obstetric outcome. Results. There were no thromboembolic events during therapy, few side effects of treatment and no osteoporotic fractures or episodes of heparin-induced thrombocytopenia. The 166 pregnancies resulted in 159 live infants. There was a significantly higher risk of preterm delivery (13% vs. 6%) and intrauterine growth restriction (4.4% vs. 3.5%). Delivery by cesarean section was more common in these high-risk LMWH-treated pregnancies (33.1%) than in untreated pregnancies (19.2%). In the LMWH-group, the occurrence of PPH was 7.2% compared with 8.8% in the matched untreated control group (p = 0.675). None of the events in the LMWH group were serious and all 166 women were in good health at discharge. Conclusions. Individually dosed LMWH is well tolerated and safe for prophylaxis and treatment of thromboembolic complications during pregnancy, delivery and the postpartum period.