Which conditions require anticoagulation during pregnancy even without a history of VTE?

Factor V Leiden homozygous is a condition that significantly increases the risk of venous thromboembolism (VTE) during pregnancy, even in the absence of a previous history of VTE. This genetic mutation leads to a hypercoagulable state due to resistance to activated protein C, which normally helps to regulate clot formation.

In pregnant individuals with this homozygous condition, the risk of developing thrombosis increases substantially because pregnancy itself is a pro-thrombotic state due to factors like increased levels of clotting factors and venous stasis. Consequently, anticoagulation is often recommended to mitigate this risk, even for patients without a personal history of thromboembolic events.

In contrast, other conditions listed such as Protein C deficiency, PT G20210A heterozygous, and Protein S deficiency may have variable recommendations regarding anticoagulation based on the patient's history, family history, and the presence of other risk factors. While these conditions can also increase the risk of VTE, they do not universally mandate anticoagulation during pregnancy as Factor V Leiden homozygous does.