The effect of thrombophylaxis on pregnancy outcome in patients with recurrent pregnancy loss associated with factor V Leiden mutation

Objective To observe the effect of thrombophylaxis on pregnancy in women with a history of unexplained recurrent pregnancy loss also carrying the factor V Leiden mutation. Methods Between 1 January and 31 December 1996, activated protein C (APC) resistance and factor V Leiden mutation were prospectively measured in 56 nonpregnant women, with a history of two or more unexplained recurrent pregnancy losses. During the same study period, seven women carrying the factor V Leiden mutation conceived, and were subsequently followed throughout their pregnancy. Subcutaneous low molecular weight heparin (LMWH, enoxaparin, 40 mg/day) and oral low dose aspirin (100 mg/day) were administered throughout the pregnancies, starting at early first trimester. Ultrasound and Doppler umbilical and fetal middle cerebral arterial flow studies were performed in the second and third trimesters, and the course and outcome of the pregnancies were documented. Results Activated protein C resistance and factor V Leiden were found in 20 (36%) and 12 (21%) women of the study, respectively. Five of the seven pregnancies occuring progressed uneventfully to term with normal fetal growth, normal Doppler flow studies and uneventful neonatal outcome. Two of the seven women had early missed abortions. Conclusions Thrombophylaxis, beginning in early pregnancy, in women with unexplained recurrent pregnancy loss associated with factor V Leiden mutation, seems to be safe and allow normal fetal development and good neonatal outcome. To prove the efficacy of thrombophylaxis by LMWH and low dose aspirin in this setting prospective controlled studies seem to be justified.