Bone health: what testing adds to the picture
October 9, 2026
In short: blood immune tests can’t tell you what is happening in the womb, but they can be a useful signal of inflammation that may affect fertility.
If you watched RTÉ Investigates: Fertility Uncovered last week, you may be wondering whether immune testing has any place in fertility care. Many of the couples we see have been through failed IVF cycles or repeated miscarriage, and some have had their NK cells or the “Chicago bloods” tested along the way.
The programme raised important questions about immune testing and treatment, and we agree with some of its key points. We also want to add some context: how these tests can be useful when they are interpreted carefully, and how we use them alongside the care your fertility clinic provides.
Key messages from RTÉ Investigates: Fertility Uncovered, and what we would add…
“The immune system doesn’t reject the embryo.”
Professor Ashley Moffett told RTÉ that the idea that the mother’s immune system can reject the foetus is wrong.
Our view: We agree, in the sense that your body does not reject an embryo the way it might reject a transplanted organ. But the immune system can still play a part. Ongoing inflammation in the body or the womb can make it harder to conceive and stay pregnant.
“Blood NK tests don’t tell you about the womb.”
Our view: We agree that blood NK cells are not the same as NK cells in the womb. Uterine NK cells are however called “natural killer” cells because they belong to the same family of immune cells, and that is their correct name. In the womb their main job is to help build the blood supply to the placenta, and a regular blood test cannot tell you what they are doing. The immune environment of the womb does appear to be different though in some women with recurrent miscarriage or failed IVF, and more research is needed to understand what that means.
“Immune treatments have limited evidence.”
Our view: We agree that the evidence for steroids, intralipids and IVIG is still developing, and decisions about them belong with your fertility doctor, who knows your full history.
So why do we still use immune tests?
We use immune markers as a signal, not a diagnosis. A raised NK cell count, high NK activation or an imbalance in cytokines can mean your body is in a more inflamed state than it should be.
That matters, because inflammation and autoimmunity are linked to fertility.
Women with active inflammatory conditions, such as rheumatoid arthritis, take longer to conceive, and the more active the disease, the longer it takes.
Thyroid antibodies are found in about one in five women with infertility, and are linked to poorer IVF outcomes even when thyroid function is normal.
In one trial, women with raised inflammation (measured by CRP) had a live birth rate of 44% on placebo, rising to 59% with low-dose aspirin. Women without raised inflammation saw no benefit.
In other words, raised inflammatory markers can point upstream, to something we may be able to modify.
Where does the inflammation come from?
Sometimes there is a clear cause, such as a diagnosed autoimmune condition. Often there isn’t, and the source of inflammation may not be obvious. When markers are raised, these are the areas we look at first, because each has evidence linking it to inflammation and fertility:
Thyroid: thyroid antibodies are a sign of autoimmunity. They are common in women with fertility problems and are linked to poorer IVF outcomes, even when thyroid hormone levels are normal.
Gut microbiome: the gut is the body’s largest point of contact with the immune system, and its bacteria help keep inflammation in balance. When that balance is disturbed, inflammation can spread beyond the gut.
Vaginal microbiome and endometrial environment: a healthy vaginal microbiome is dominated by Lactobacillus bacteria, which keep the environment acidic and calm. When they are low, local inflammation can rise, and this is linked to miscarriage and failed implantation. Chronic endometritis, a low-grade inflammation of the womb lining, is also more common in repeated IVF failure. These need local tests, not blood tests.
Nutrients: vitamin D, omega-3, iron and zinc all help regulate the immune system. Low levels are common and simple to correct.
What we do with the results
We read your immune results alongside your history, diet and lifestyle, rather than on their own. Then we focus on low-risk steps that are worth doing for your general health anyway:
– identifying and addressing autoimmunity, especially of the thyroid
– investigating and supporting the gut microbiome and vaginal microbiome
– improving diet quality and correcting vitamin D and other nutrient deficiencies, using tailored supplements to support the body’s anti-inflammatory pathways where appropriate
We don’t prescribe immune treatments. Where they are considered, that is a decision for your fertility doctor, and we are happy to work alongside them.
A note on the “Chicago bloods”
The “Chicago bloods” is a panel of immune tests from a laboratory in Chicago, including NK cell counts and activity and a Th1/Th2 ratio. The Th1/Th2 ratio doesn’t directly measure Th1 or Th2 cells. It measures which cytokines your T cells can make when stimulated in a test tube, not inflammation that is active in your body. A high ratio can also mean low anti-inflammatory IL-10 rather than too much inflammation, so it is the numbers behind the ratio that matter.
What we test
Through a Eurofins laboratory, we measure the T helper cells directly (Th1, Th2, Th17 and regulatory T cells), alongside inflammatory cytokine levels in the blood, and NK cell numbers and activity. This gives a clearer picture of which part of the immune system has shifted. All of our test results are reviewed by our Director of Research Ciara Wright PhD who has a background in immunology and cellular biology, along with a clinical diploma in medical laboratory sciences.
The bottom line
Not every embryo implants, even when everything looks perfect. But if nothing has changed since the last transfer, it is worth asking whether something could be improved before the next one. When embryos are few and every transfer is precious, it makes sense to look for anything that could be improved first, balanced against age and time.
For the full evidence, with references, read our Clinical Review – NK cell and immune blood tests in fertility and miscarriage: what the evidence shows: Link: Clinical Reviews – Positive Nutrition Ciara Wright PhD
Positive Nutrition offers immune and nutritional testing, and nutritional support for fertility. If you would like more information about the services we offer, including testing, please get in touch
