Pregnancy and Elevated Factor VIII

Hereditary deficiency of clotting factor VIII is called hemophilia A, which occurs most often in men; women are carriers of the disease.

Recently, we are increasingly encountering situations where women are prescribed testing of factor VIII levels to rule out elevation. 🤷‍♀️ This recommendation is based on the assumption that high levels of factor VIII lead to thrombosis (and this does have some support — when ultra-high doses of factor VIII are given even to patients with hemophilia, thrombosis may indeed occur 🧏‍♀️).

So, is it really necessary to measure factor VIII levels when investigating pregnancy loss or thrombosis?

Normal activity of factor VIII (Abbassi-Ghanavati M et al., 2009): 🔴 General population: 50–150% 🔴 1st trimester: 90–210% 🔴 2nd trimester: 97–312% 🔴 3rd trimester: 143–353%

Elevation of factor VIII activity is physiological in pregnancy 🧏‍♂️ and is most pronounced closer to delivery.

In earlier publications (up to the mid-2010s), based on small and mostly retrospective studies, conclusions were drawn that factor VIII >150% increases the risk of early miscarriages. However, in more robust prospective studies, this association has not been confirmed. 👍

👉 Therefore, for the purpose of diagnosing thrombophilia, measuring factor VIII activity — especially during pregnancy — is not meaningful. ⛔⚠️

Algorithm for detecting lupus anticoagulant Hereditary Thrombophilias and Pregnancy