Getting pregnant is a process that requires several steps to work together. For some couples, the issue is not related to hormones or physical issues. Rather, the body’s defence system is the problem. When immune system infertility occurs, the body thinks sperm or an embryo is a threat.
What is Immunological Infertility?
Immunological infertility is when your body’s defence system affects getting pregnant. Your immune system is what keeps you from getting sick. It fights off invaders like bacteria. However, in some cases, the immune system attacks sperm or an embryo.
This type of immune system infertility affects roughly 5 to 20% of couples, due to which they are unable to conceive. The numbers might be higher because immune problems are not always tested during regular checkups.
How the Immune System Impacts Fertility
During pregnancy, a woman’s body must accept an embryo with DNA from both parents. Usually, a specific type of immune cell creates a safe environment for the embryo to attach and grow. But when this balance is upset, fertility problems occur. The immune system can attack reproductive cells or interfere with implantation, causing problems with conception or miscarriages.
Anti-Sperm Antibodies: An Immune System Issue
Another very common instance of immune system issues related to fertility is anti-sperm antibodies. These are immune system proteins that attack sperm cells and may be present in both men and women.
In Men
In men, anti-sperm antibodies are normally present when the immune system barrier surrounding the testicles is damaged. This can occur due to:
Damage to the testicles
Infections like prostatitis or epididymitis
Surgery, including vasectomies
Testicular torsion
Varicocele (swelling of veins in the scrotum)
When this happens, sperm cells encounter the immune system, which produces antibodies against them. Studies have shown that immune system issues are responsible for 12 to 13% of male infertility. However, not all men with anti-sperm antibodies have fertility issues.
In Women
Women can also develop anti-sperm antibodies, although this is less likely. This can happen because of the following reasons:
There is damage to the lining of the vagina or cervix.
There are sexually transmitted infections.
There is endometriosis.
There is inflammation of the cervix.
These antibodies in the cervical fluid prevent the sperm from reaching the egg.
How Anti-Sperm Antibodies Affect Fertility
When anti-sperm antibodies bind to the sperm, the following issues occur:
Issues with Sperm Movement: Antibodies slow sperm or cause them to clump.
Issues with Binding: The antibodies prevent the sperm from fusing with the egg.
Issues with Fertilisation: The antibodies can prevent fertilisation.
Issues with Implantation: Antibodies can prevent embryo development.
The likelihood of experiencing these fertility issues depends on the number of sperm that are bound by antibodies. If more than 50% of the sperm are bound by antibodies, fertility problems are more likely.
Other Immune-Related Fertility Issues
Apart from anti-sperm antibodies, other immune-related issues may occur, which affect fertility:
Autoimmune Diseases
Lupus and thyroid problems are examples of autoimmune diseases in which the immune system attacks the body’s own tissues, affecting hormone regulation and reproductive functions.
Natural Killer Cell Problems
An overabundance of NK cells in the uterus impairs implantation.
Regulatory T Cell Imbalances
Regulatory T cells (also known as Treg cells) promote immune tolerance to the embryo. When these cells are not functioning properly, the risk of miscarriage increases.
Diagnosis of Immunological Infertility
Finding immune-related causes needs specific testing:
Blood Tests: Check for antibodies affecting fertility
Sperm Antibody Tests: The Immunobead test shows if antibodies attach to sperm
Endometrial Biopsy: A tissue sample is examined for immune cell problems
Postcoital Test: Checks cervical mucus after intercourse
NK Cell Testing: Measures natural killer cell numbers and activity
These tests usually happen after multiple failed conception attempts or repeated pregnancy losses.
Treatment Options
Several treatments help couples with immune system infertility:
Assisted Reproductive Technology
Intrauterine insemination (IUI) bypasses cervical mucus, where antibodies might be hiding, placing washed sperm straight into the uterus.
In-vitro Fertilization (IVF) fertilises eggs in a lab, beating antibody-related problems.
Intracytoplasmic Sperm Injection (ICSI) involves injecting sperm directly into an egg and is effective when many sperm are coated with antibodies.
Medical Treatments
Corticosteroids can reduce immune system function, but they must be closely monitored. Controlling the underlying autoimmune disease can also help with fertility.
Sperm Washing
Sperm can be separated from antibodies in a laboratory, potentially improving sperm quality for fertility treatments.
Conclusion
Studies on immune-related factors in fertility are increasing. Researchers are trying to understand how immune tolerance develops during pregnancy. If you've been trying to conceive without success or have had repeated pregnancy losses, talk with a fertility specialist about immune testing. While not always necessary, these tests can provide answers when standard evaluations don't reveal a clear cause. Having an immune-related fertility issue doesn't mean pregnancy is impossible. Many couples get pregnant with proper treatment and support.