Dalteparin for the prevention of recurrence of placental-mediated complications of pregnancy in women without thrombophilia: a pilot randomized controlled trial

Background: The role of anticoagulants for the prevention of placental-mediated pregnancy complications is uncertain. Objectives: Our aim was to investigate the effectiveness of dalteparin, a low-molecular-weight heparin, in preventing the recurrence of these complications in women without thrombophilia. Patients/methods: Between August 1 2000 and June 20 2007, 116 pregnant women with: (i) <= 16 weeks' gestation, (ii) no detectable thrombophilia, (iii) previous severe pre-eclampsia, newborn weight <= 5th percentile, unexplained intrauterine death or abruptio placentae were randomized to either a prophylactic daily dose of dalteparin (n = 58) or no dalteparin (n = 58). The primary outcome was a composite of one or more of: severe pre-eclampsia, newborn weight <= 5th percentile or major abruptio placentae. Secondary outcomes included non-severe pre-eclampsia, newborn weight at the 6-10th percentile and gestational age at delivery. Analyses were by intention to treat. P < 0.05 was considered to be significant. This study is registered as an International Standard Randomized Controlled Trial, number ISRCTN78732833. Results: Among the 110 women included in the final analysis, dalteparin was associated with a lower rate of the primary outcome [5.5% (n = 3/55) vs. 23.6% (n = 13/55), adjusted odds ratio (OR) 0.15, 95% confidence interval (CI) 0.03-0.70]. Secondary outcomes were not statistically different between the groups. Bleeding problems or thrombocytopenia did not occur. Conclusion: In this pilot study, dalteparin is effective in decreasing the recurrence of placental-mediated complications in women without thrombophilia. Our results require confirmation in further randomized trials.