Effectiveness and safety of thromboprophylaxis with enoxaparin for prevention of pregnancy‐associated venous thromboembolism

Abstract

Unlabelled Box BackgroundLow‐molecular‐weight heparin is used to prevent pregnancy‐associated venous thromboembolism (PA‐VTE), but there are limited data to inform which women require thromboprophylaxis in pregnancy and debate about which low‐molecular‐weight heparin dose is effective and safe. AimsTo evaluate the efficacy and rate of complications using enoxaparin for thromboprophylaxis in a cohort of women at risk of PA‐VTE managed between 1999 and 2014 at National Women's Hospital, a tertiary obstetric referral center in Auckland, New Zealand. MethodsA retrospective, observational study of women who received thromboprophylaxis with enoxaparin for prevention of PA‐VTE while under the care of the obstetric or maternal fetal medicine team. ResultsA total of 172 pregnancies in 123 women were identified. A single daily dose of 40 mg enoxaparin was used in 94.8% of pregnancies. Two breakthrough PA‐VTEs occurred (1.2% [95% confidence interval, 0.32‐4.14]). Postpartum hemorrhage ≥500 mL was reported in 36.6% of births and postpartum hemorrhage ≥1000 mL in 9.3% of births. Only four women were transfused. Neuraxial analgesia/anesthesia was used in 52.4% of births, including 39.6% of vaginal births. ConclusionUse of standard doses enoxaparin thromboprophylaxis in our cohort was effective at preventing PA‐VTE. Neuraxial analgesia/anesthesia was used frequently during labor and birth;, using higher doses of enoxaparin may limit access to this. Postpartum hemorrhage was common and higher doses of thromboprophylaxis may increase obstetric bleeding complications. These data do not suggest an urgent need to consider higher doses of enoxaparin for thromboprophylaxis in this clinical setting.