The incidence and risk factors of recurrent venous thromboembolism during pregnancy.
BACKGROUND
Recurrent venous thromboembolism (VTE) during pregnancy is a challenging topic with relatively few publications. The aim of this study was to identify the incidence and the risk factors of recurrent antepartum VTE in women with a history of at least one previous VTE episode.


METHODS
This observational cohort study involved 270 pregnant women (369 pregnancies) with at least one previous episode of VTE. The risk factors of recurrent antepartum VTE were identified by using group A (women without recurrent venous thromboembolism VTE) as a control group for group B (women with recurrent VTE despite LMWH (low molecular weight heparin) prophylaxis) and C (women with VTE recurrence in early pregnancy before the planned initiation of LMWH prophylaxis).


CONCLUSIONS
The incidence of recurrent VTE was 7.6% (n=28). Twelve recurrent VTEs in ten women (3.3%) developed during early pregnancy before initiation of LMWH and sixteen recurrent VTEs (4.3%) developed in 15 women despite LMWH prophylaxis. In women with recurrent antepartum VTE, the incidence of a history of two or more previous VTEs (group A vs. B: 5.7% vs. 40.0%, p<0.001; group A vs. C: 5.7% vs. 30.0%, p=0.022), previous VTE in connection with antiphospholipid antibody syndrome (group A vs. B: 2.6% vs. 20.0%, p=0.012) and a history of VTE related to hormonal risk factors (group A vs. B: 60.4% vs. 93.3%, p=0.011) was significantly higher compared to those with successful LMWH-prophylaxis. The percentage of the women with long-term anticoagulation was also significantly higher among the women with recurrent antepartum VTE (group A vs. B: 7.6% vs. 46.7%, p<0.001) compared to those with successful LMWH-prophylaxis. The risk of antepartum recurrent VTE is considerable in women with a history of two or more previous VTEs, antiphospholipid antibody syndrome or long-term anticoagulation. The antepartum prophylaxis with prophylactic dose of LMWH or even with intermediate dose of LMWH might not be sufficient in this high-risk population.
Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, Finland. Electronic address: paivi.galambosi@gmail.com.
Päivi J
PJ
Galambosi
Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, Finland.
Veli-Matti
VM
Ulander
Turku University and Satakunta Central Hospital, Pori, Finland.
Risto J
RJ
Kaaja
D000328:Adult; D000925:Anticoagulants / Q000627:therapeutic use*; D015331:Cohort Studies; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use*; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology* / Q000517:prevention & control*; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000453:epidemiology* / Q000517:prevention & control*
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight
Low-molecular-weight heparin; Pregnancy; Risk factors; Thrombophilia; Venous thromboembolism