Prevention of venous thromboembolism in pregnant patients with a history of venous thromboembolic disease: A retrospective cohort study

Background: Optimal prophylactic strategies in pregnant women with a history of venous thromboembolism (VTE) are unknown.

Patients and methods: We conducted a retrospective cohort study of consecutive pregnant patients with a previous VTE history. Patients were followed until 6 weeks postpartum. Patients with a previous unprovoked event (including antepartum VTE) received antenatal prophylaxis, mostly with low dose low molecular weight heparin (LMWH). All patients received prophylaxis for six weeks after delivery.

Results: We included a total of 199 pregnancies in 142 women. Of these, 147 pregnancies occurred in women with unprovoked or estrogen-related VTE history and 52 pregnancies in women with provoked VTE. There were 8 recurrences in 199 pregnancies (4%; 95%CI: 2.05-7.73), of which 5 were antepartum recurrences (2.5%; 95%CI 1.08-5.75) and 3 were postpartum (1.5%; 95% CI 0.51-4.34). In the unprovoked VTE group there were 7 recurrences (4.7%; 95%CI: 2.32-9.50), whereas in the provoked VTE group there was 1 (1.9%; 95%CI: 0.34-10.12). There was one major bleeding event in a patient not receiving LMWH secondary to placental abruption.

Conclusion: This study suggests that the use of prophylactic doses of LMWH during pregnancy and puerperium, as described in this study, results in low occurrence of ante- and postpartum VTE recurrences in patients with previous VTE. Further studies are required to confirm this observation.