Published 1 Nov, 2025
2 min. read

The KIR/HLA-C Test – When It Is Indicated and What the Results Reveal

Learn when the KIR/HLA-C test is recommended, how it works, and what the results mean for couples with implantation failure or recurrent miscarriage.

The KIR/HLA-C Test – When It Is Indicated and What the Results Reveal

The KIR/HLA-C test may be recommended by a fertility specialist when a patient experiences repeated embryo implantation failures or recurrent miscarriages.

Below is a clearer explanation of what this test involves and what the results can indicate.

“You deserve to be heard, seen, treated with respect, and supported throughout your life.”

Ilustrație cu Dr. Andreas Vythoulkas oferind sprijin și îngrijire personalizată unei paciente în cadrul tratamentelor FIV.
Ilustrație cu o femeie însărcinată reprezentând succesul tratamentelor de fertilitate oferite de Dr. Andreas Vythoulkas.

Why the KIR/HLA-C Test Is Recommended

Uterine adaptation to the fetus is a complex immunological process that involves the interaction between KIR receptors (Killer Immunoglobulin Receptors) expressed by maternal immune cells in the uterus (NK cells) and their ligands, known as HLA-C (Human Leukocyte Antigen-C).

The risk that the maternal immune system might “reject” the embryo can be evaluated through the genetically determined immune compatibility test KIR/HLA-C.

This blood test helps the physician determine the most appropriate therapeutic protocol for couples facing infertility.

The KIR/HLA-C test may be indicated in the following situations:

  • Repeated IVF failures (implantation failure)
  • Recurrent pregnancy loss (repeated miscarriages)
  • History of preeclampsia or preterm birth
  • Before IVF with donated oocytes (to assess compatibility between donor and recipient)
  • To determine the optimal number of embryos for transfer

How the KIR/HLA-C Test Is Performed

The test involves collecting a blood sample from both partners and, when donor eggs or sperm are used, from the donor as well.

The results, interpreted by a genetic specialist, can help identify an immunologic cause of infertility and guide the most suitable treatment plan.

KIR/HLA-C Incompatibility: What Can Be Done?

If the results show KIR/HLA-C incompatibility, the fertility specialist can tailor the therapeutic approach accordingly.

Options may include:

  • immunomodulatory treatment for the woman (to increase immunological tolerance)
  • transferring a single embryo (to avoid potential dual exposure to incompatible HLA-C)
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The KIR/HLA-C Test

If you have questions related to the KIR/HLA-C test or would like recommendations on evaluating and monitoring your newborn during the first days of life, you may request an individual consultation at any time. A thorough assessment helps determine the most suitable monitoring and support plan for your child.
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