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Table 20-5

Inherited Thrombophilias and Risk of Venous Thromboembolism (VTE) in Pregnancya

ThrombophiliaVTE Risk per Pregnancy (No History) (%)VTE Risk per Pregnancy (Previous VTE) (%)Percentage of All VTE
Factor V Leiden homozygosity2-14172
Prothrombin G20210A homozygosity2-4>170.5
Factor V Leiden heterozygous0.5-31040
Prothrombin G20210A heterozygous0.4-2.6>1017
Protein C deficiency0.1-1.74-1714
Antithrombin deficiency0.2-11.6401
Protein S deficiency0.3-6.60-223
Factor V Leiden + prothrombin G20210A (compound heterozygosity)4-8>201-3

aAdapted with permission from American College of Obstetricians and Gynecologists Committee on Practice BulletinsObstetrics. ACOG Practice Bulletin No. 197: inherited thrombophilias in pregnancy. Obstet Gynecol. 2018;132(1):e18-e34. Copyright © 2018 by The American College of Obstetricians and Gynecologists.