Prophylaxis with Low Molecular Weight Heparin for Prevention of Placenta-related Recurrent Adverse Pregnancy Outcomes

Aims: To determine whether antenatal administration of low-molecular-weight-heparin (LMWH) reduces the recurrence of adverse pregnancy outcomes (APO).

Study Design: Retrospective cohort study.

Place and Duration of the Study: Inova Alexandria Hospital, Alexandria, VA and Georgetown University Medical Center, Washington, DC during the period of January 1, 2006 and December 31, 2009.

Methodology: All pregnant women with history of APOs, including preeclampsia or abruption at <35 weeks, birth weight <5th centile, fetal loss at ≥20 weeks, or ≥2 spontaneous losses between 12 and 20 weeks, were administered LMWH or not at the discretion of the managing physician. Excluded were cases with antiphospholipid syndrome. The independent effect of LMWH on recurrence was assessed using logistic regression analysis with odds ratios (OR) having 95% confidence interval (CI) not inclusive of the unity considered significant.

Results: Of the 140 women in the cohort, 44 (31%) received LMWH during the subsequent pregnancy and the remainder did not. APO recurred in 23.6% (33/140). Logistic regression analysis demonstrated that LMWH significantly and independently lowered the risk of recurrent APO (adjusted OR=0.08, 95% CI 0.01-0.45), whereas history of fetal growth restriction (OR=3.88, 95% CI 1.51-9.99) and positive results for inherited thrombophilias (OR=6.96, 95% CI 1.58-30.67) increased the risk.

Conclusion: In patients with rigorously defined history of severe APO, prophylaxis with LMWH is associated with a significant reduction in recurrence of severe APO.