Addition of enoxaparin to aspirin for the secondary prevention of placental vascular complications in women with severe pre-eclampsia

Administration of heparin in the secondary prevention of placental vascular complications is still experimental. In women with a previous severe pre-eclampsia, we investigated the effectiveness of enoxaparin, a low-molecular-weight heparin, in preventing these complications. Between January 2000 and January 2010, 224 women from the NOHA First cohort, with previous severe pre-eclampsia but no foetal loss during their first pregnancy and negative for antiphospholipid antibodies, were randomised to either a prophylactic daily dose of enoxaparin starting from the positive pregnancy test (n=112), or no enoxaparin (n=112). The primary outcome was a composite of at least one of the following: pre-eclampsia, abruptio placentae, birthweight ≤ 5th percentile, or foetal loss after 20 weeks. Enoxaparin was associated with a lower frequency of primary outcome: 8.9% (n=10/112) vs. 25 % (28/112), p=0.004, hazard ratio = 0.32, 95% confidence interval (0.16-0.66), p=0.002. Enoxaparin was safe, with no obvious side-effect, no thrombocytopenia nor major bleeding event excess. This pilot study shows that enoxaparin given early during the second pregnancy decreases the occurrence of placental vascular complications in women with a previous severe pre-eclampsia during their first pregnancy.