Anticoagulation during pregnancy in patients with a prosthetic heart valve

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Effective anticoagulation is mandatory for pregnant women with mechanical heart valves. Oral anticoagulants offer the best maternal protection against thrombosis, but their use might be associated with an appreciable risk of fetal malformations and pregnancy loss. By contrast, heparin derivatives are associated with a reduced risk of fetal damage, but an increased risk of valve thrombosis in the mother, even with appropriate dose adjustment and monitoring of therapeutic efficacy. Given the varying risks of available anticoagulation strategies, and the paucity of data to inform the optimal approach, no single accepted treatment option exists for pregnant women with mechanical prosthetic valves. Although low-molecular-weight heparin is considered more efficacious than unfractionated heparin, treatment failures, even at therapeutic levels of factor Xa inhibition, have been reported. The risk of warfarin-related embryopathy might be overstated, particularly at doses ≤5 mg daily. We advocate an individualized anticoagulation strategy that takes into account the patient's preferences, calls for the use of vitamin K antagonists throughout pregnancy (substituted with a heparin derivative only close to term) for those patients at the greatest risk of thromboembolism, and relies on close multidisciplinary collaboration between the cardiac and obstetric care teams.

Key Points

  • The management of pregnant women with prosthetic heart valves is a clinical challenge

  • No clear consensus exists on the optimal artificial valve and anticoagulation strategy for these women, owing to the paucity of data that can guide therapeutic decisions

  • Cardiac and obstetric care teams need to work collaboratively to help these patients make personalized decisions that consider the risks and benefits of various therapies

  • Consistent monitoring to maintain effective anticoagulation is crucial, regardless of the chosen treatment strategy

  • Warfarin throughout pregnancy might be appropriate for selected patients, particularly those at increased risk of thromboembolism and when the risk of adverse fetal outcomes is comparatively low

  • Heparin derivatives pose no direct risk to the fetus, but are limited by an appreciable risk of maternal thromboembolic complications, even in patients with seemingly therapeutic levels of anticoagulation

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Figure 1: Proposed algorithm for anticoagulation therapy during pregnancy in women with prosthetic heart valves.


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J. M. Castellano, R. Narayan, and P. Vaishnava researched the data for the article. All the authors provided substantial contributions to discussions of its content, wrote the article, and reviewed and/or edited the manuscript before submission.

Correspondence to Jose M. Castellano.

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Castellano, J., Narayan, R., Vaishnava, P. et al. Anticoagulation during pregnancy in patients with a prosthetic heart valve. Nat Rev Cardiol 9, 415–424 (2012) doi:10.1038/nrcardio.2012.69

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