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Efficacy of enoxaparin for improving pregnancy outcomes and uteroplacental blood flow in women with thrombophilia and recurrent pregnancy loss

      Objective

      Maternal thrombophilia is associated with recurrent pregnancy loss (RPL). Prophylaxis with low-molecular-weight heparin can benefit women with thrombophilia and RPL. There is little information about the effect of such treatment on uteroplacental blood flow. The purpose of this study was to evaluate the efficacy of two doses of enoxaparin for improving pregnancy outcomes and to invesigate the effect on uteroplacental blood flow.

      Study design

      This multicentre, prospective, randomised, open-label study compared pregnancy outcome in women with thrombophilia and recurrent pregnancy loss (3 losses in first trimester, 2 losses in second trimester or 1 loss in third trimester) receiving enoxaparin 40 mg/day or 80 mg/day (40 mg twice daily). Women were enrolled at 5–10 weeks gestation and received enoxaparin throughout pregnancy and post-partum. The primary efficacy endpoints were the delivery of a live, healthy infant and Doppler indices in the uterine and umbilical arteries.

      Results

      Prophylaxis with enoxaparin significantly increased the rate of live birth (84.3% vs 28.2% for 40 mg/day, 78.3% vs 28.3% for 80 mg/day; P=.001), decreased the rate of pre-eclampsia (3.4% vs 6.7% for 40 mg/day, 4.4% vs 14.3% for 80 mg/day; P=.001) and decreased the rate of placental abruption (4.5% vs 13.5% for 40 mg/day, 3.3% vs 8.8% for 80 mg/day; P=.002) compared with patients´ historical rates. The pulsatility index was significantly lower in the uterine arteries of women who received 80 mg/day compare to those receiving 40 mg/day, between 30-34 weeks (1.2 ± 0.08, vs 1.5 ± 0.15, respectively P < .05). No other significant differences in efficacy or safety were observed between the two enoxaparin groups.

      Conclusion

      Enoxaparin increased the rate of live births in thrombophilic women with recurrent pregnanchy loss. A dose of 40 mg/day was sufficient to significantly improve pregnancy outcome. Improved uteroplacental blood flow in the group receiving the higher dose of enoxaparin suggests that this dose should be considered in women with multiple thrombophilic defects.