How to Interpret HLA Matching in Reproductive Immunology?
UPDATED ON 16 JUNE 2025

If you’re facing repeated implantation failures or recurrent miscarriages, you may have come across the term HLA matching and wondered what it really means and how it affects your fertility journey.
I’m Dr. Jay Mehta, a reproductive immunologist in India, here to explain this in a clear, understandable way, as someone who combines expertise in reproductive immunology with a compassionate approach to patient care.
AUTHOR
Dr Jay Mehta
Scientific Director & IVF Specialist with 10+ years of experience
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What is HLA and Why Does It Matter?
HLA stands for Human Leukocyte Antigen, which is a group of proteins found on the surface of most cells in your body. These proteins act like ID badges, helping your immune system recognize what belongs to you and what is foreign. This protective mechanism is critical for defending your body against infections and foreign invaders.
HLA testing is typically done when we are involved in transplant medicine, specifically for organ transplants.
This is because if the HLA matching is similar, especially between father and son, mother and daughter, father and daughter, or any person having a blood relation, then the body may recognise that the transplanted organ is not foreign and will reduce its rejection mechanism, thereby allowing for greater graft acceptance rates.
How Is HLA Matching Different in Reproductive Immunology?
However, this is the exact opposite mechanism which works in reproductive science. Unlike transplant medicine where similarity is good, greater HLA mismatch between partners can actually benefit pregnancy success.
When the HLA types of partners are too similar, especially in cases of close blood relation marriages (also called consanguineous marriages), it may increase the risk of implantation failure and a higher risk of developing abortions. This happens because the immune system might not be triggered adequately to support the pregnancy, leading to complications.
Who Should Consider HLA Typing?
HLA typing is commonly done as a part of reproductive immunology. We usually recommend HLA typing for couples experiencing:
- Multiple miscarriages (abortions)
- Recurrent implantation failure in IVF
- Unexplained pregnancy losses despite good embryo quality
This test involves a simple blood sample from both partners and usually takes about two weeks to process.
What Specific HLA Types Are Important?
While HLA involves many subtypes, we focus especially on HLA-C and a related factor called KIR genotype in reproductive immunology. Research shows:
- When partners share more than 45-50% similarity in HLA-C types, it might increase the risk of recurrent miscarriages and implantation failures.
- However, it’s important to remember that HLA-C is highly variable (polymorphic), and many couples with high HLA-C similarity still have healthy pregnancies without any issues.
This means HLA matching is one piece of the puzzle, not the sole cause of pregnancy problems.
When is HLA Matching Most Useful?
We don’t recommend HLA typing for every couple with a history of miscarriage. But it becomes very helpful before starting certain treatments like paternal lymphocyte immunization therapy (LIT), an advanced immunological therapy designed to help the immune system support pregnancy.
Each couple’s case is unique, so we discuss HLA matching and its implications in detail, tailoring treatment accordingly.

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Beyond HLA-C: The Role of HLA-G in Pregnancy
HLA matching and recurrent abortions is a very vast topic and further detailing is done for the couples on a case to case basis.
Another key player in pregnancy is HLA-G, a special antigen expressed by the placenta and fetus. HLA-G interacts closely with uterine natural killer (NK) cells — immune cells in the womb that help regulate the environment for the growing baby.
Scientists are still researching exactly how this interaction works, but it’s clear that HLA-G plays an important role in maintaining a healthy pregnancy.
Final Thoughts: Understanding HLA Matching in Your Fertility Journey
HLA matching is a complex but important aspect of reproductive immunology. It helps us understand why some couples face recurrent pregnancy losses or implantation failures and guides us in choosing the right treatment approach.
If you’re struggling with unexplained fertility issues, discussing HLA typing with your fertility specialist could provide valuable insights. Remember, no single test gives all the answers—but together, we can piece the puzzle to give you the best chance of a healthy pregnancy.
FAQs About HLA Matching and Fertility
- Is HLA matching the cause of all miscarriages?
No, miscarriages have many causes. HLA matching is just one factor among others like egg quality, sperm health, and hormonal balance.
2. How long does HLA testing take?
Typically, about two weeks from blood sample collection.
3. Does HLA matching guarantee pregnancy success?
No test can guarantee success, but understanding HLA compatibility can help personalize your treatment plan.
If you have any questions or want to discuss whether HLA testing is right for you, feel free to call us at 1800-268-4000. Your journey matters, and together we can explore the best options for you.
AUTHOR
Dr Jay Mehta
Scientific Director & IVF Specialist with 10+ years of experience
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