Reproductive Immunology

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated July 25, 2026

Reproductive Immunology is the study of immune system contributions to implantation failure, recurrent pregnancy loss, and fertility-related conditions. Research in this field has clarified several immune pathways relevant to reproductive outcomes. Antiphospholipid syndrome (APS) elevates thrombotic risk at implantation sites and is a treatable cause of recurrent pregnancy loss, a causal link the European Society of Human Reproduction and Embryology's recurrent pregnancy loss guideline confirms because APS carries a reproducible laboratory diagnostic standard.¹² Elevated uterine natural killer cell activity is a proposed contributor to otherwise unexplained implantation failure, and it remains an area RRM clinicians evaluate even though that same guideline, scoped to recurrent pregnancy loss rather than implantation failure, currently finds the evidence insufficient to endorse routine testing. Proving causation requires a reproducible way to define and measure the target, and no such standard yet exists for uterine natural killer cell activity. That is a gap in method, not evidence against an immune contributor. Chronic endometritis disrupts the endometrial environment and associates with recurrent implantation failure and pregnancy loss.³ The endometrial microbiome is an adjacent area of investigation: microbial imbalance in the uterine environment correlates with implantation outcomes independent of structural pathology.⁴ RRM clinicians may incorporate reproductive immunology evaluation when the clinical picture suggests an immune contributor, particularly in couples with recurrent pregnancy loss or thrombophilia.

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.