What is the role of inherited thrombophilia testing in RPL?

Routine testing for inherited thrombophilia is not recommended in recurrent pregnancy loss. ASRM (2026) states this directly, and lists as not recommended: factor V Leiden, prothrombin gene, MTHFR, protein C, protein S, antithrombin III, and homocysteine. The evidence has moved further than many clinicians realise. A recent systematic review found the prevalence of thrombophilia in women with RPL to be the same as in the general population — that is, no association at all rather than a weak one. On treatment, ASRM states that the use of anticoagulants for RPL with hereditary thrombophilia or unexplained RPL is not recommended, based on high-quality evidence showing no benefit on live birth or miscarriage rate. A randomised trial of prophylactic LMWH in women with inherited thrombophilia and recurrent miscarriage found live birth rates of 72% treated versus 71% untreated. Where inherited thrombophilia testing is appropriate: identifying women who might benefit from anticoagulation to prevent recurrent venous thromboembolism in pregnancy, in line with haematology guidelines. That is a thrombosis indication assessed on its own merits, not a pregnancy loss indication. The distinction that causes most confusion: antiphospholipid syndrome is an ACQUIRED thrombophilia, it is associated with RPL, and it should be tested for where clinical criteria are met. Note also that if all miscarriages are aneuploid, aPL testing is not recommended.