Autoimmune/Thrombophilic Disorders (as RPL Causes)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated August 8, 2026

Autoimmune and thrombophilic disorders are a category of conditions, acquired and inherited, that elevate clotting risk or disrupt immune tolerance in ways that impair implantation, placentation, and early pregnancy maintenance. They are among the identifiable, treatable causes of recurrent pregnancy loss that thorough evaluation can uncover. Treatment works best when it targets the full profile a workup finds, not one marker alone. The category spans two overlapping groups: autoimmune conditions such as antiphospholipid syndrome and thyroid autoimmunity, and inherited thrombophilias such as Factor V Leiden, the prothrombin G20210A mutation, and protein C or S deficiency.

Inherited thrombophilias alter coagulation factor activity, increasing the likelihood of clot formation in small vessels including the placental vasculature.¹ Not all carriers experience adverse pregnancy outcomes. Clinical severity depends on mutation type, zygosity, and the presence of other risk factors. Evaluation through targeted testing can identify these conditions before a subsequent pregnancy attempt.

On the autoimmune side, antiphospholipid syndrome is the most thoroughly characterized immune cause of pregnancy loss. It has an established mechanism and a defined treatment pathway. Thyroid autoimmunity is different. Antithyroid antibodies are associated with elevated miscarriage rates even when thyroid hormone levels remain within normal reference ranges.² Whether treating that association changes outcomes is a separate question. A randomized trial, TABLET, gave levothyroxine to euthyroid women selected only for thyroid peroxidase antibody positivity. It found no improvement in live birth rate over placebo: 37.4% versus 37.9%.³ That trial tested one intervention against one marker, with any coexisting thrombophilic, immune, or uterine findings left unaddressed. A different strategy tested the opposite approach. It treated whatever combination of factors a workup actually found: thyroid dysfunction, thrombophilia, an elevated Th1/Th2 ratio, chronic endometritis. In women under 40, that combined approach produced a 78.1% live birth rate. The untreated comparison group reached 42.3% (p=0.002).⁴ The role of natural killer cell activity at the implantation site is an area of ongoing clinical investigation.

Identifying which specific condition or combination is present determines the management direction. Anticoagulation support, immune modulation, and thyroid optimization address distinct mechanisms. They are not interchangeable. Treatment follows diagnosis, not loss count.⁵

These conditions are diagnosable. Women with recurrent pregnancy loss who carry these conditions are not experiencing unexplained loss. RRM approaches recurrent pregnancy loss as a diagnostic problem rather than a diagnosis of exclusion. Related entries: thrombophilia, methylated folate and MTHFR.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.