Severe antithrombin deficiency in pregnancy: Achieving adequate anticoagulation

Area of Science:

• Obstetrics and Gynecology
• Hematology
• Pharmacology

Background:

• Antithrombin deficiency is a significant risk factor for pregnancy-associated venous thromboembolism (VTE).
• Standard anticoagulation with low molecular weight heparin (LMWH) may be less effective in antithrombin deficiency due to impaired drug-target interaction.

Observation:

• A multicentre case-series evaluated 27 pregnancies in 18 women with severe antithrombin deficiency (antithrombin level <0.55 IU/ml or <0.8 IU/ml with VTE history).
• The study assessed the LMWH dose needed to achieve therapeutic anti-activated factor X (anti-Xa) levels.

Findings:

• Women with severe antithrombin deficiency required high daily doses of LMWH, averaging 20,220 IU/day, to reach target anti-Xa levels.
• All pregnancies resulted in live births, with intrauterine growth restriction observed in 18% of cases.

Implications:

• High-dose LMWH is necessary for effective anticoagulation in pregnant women with antithrombin deficiency.
• This finding aids in optimizing VTE prophylaxis and management during pregnancy in this high-risk population.
• Further research may explore individualized dosing strategies based on anti-Xa monitoring.