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

Optimal prophylactic strategies in pregnant women with a history of venous thromboembolism (VTE) are unknown. 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. 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. 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. •Pregnant patients with previous venous thrombosis are at increased recurrence risk.•In this study we used prophylaxis mainly with low dose low molecular weight heparin.•Antepartum prophylaxis was given in cases of previous unprovoked thrombosis.•Postpartum prophylaxis was used in all patients.•We observed a low rate of ante- and postpartum recurrences.