Recurrent Miscarriage: 9 Tests Most Clinics Don't Run
You have had two losses, maybe more. You did the testing you were sent for. The results came back, and the word you were given was unexplained.
If you have been treating that word as an answer, it is worth knowing what it usually means. In recurrent loss, up to half of couples are told their losses are unexplained after a standard evaluation. Unexplained is not the same as nothing to find. More often, it means the search stopped at a familiar short list: karyotyping, a single clotting test, a look at the anatomy, and a thyroid number. Everything past that was never run.
The recommendation you were given was not careless. The question is whether the investigation behind it was complete before the word unexplained was used. This episode walks through nine areas a standard workup tends to skip, and what a more complete one looks at.
What to Know Before a Recurrent Miscarriage Workup
The definition of recurrent loss changed in 2026. The American Society for Reproductive Medicine now defines it as two or more losses, which no longer need to be consecutive, and a biochemical loss confirmed by hCG now counts. You no longer have to wait for a third loss for a full evaluation to be reasonable.
Unexplained usually describes the workup, not your biology. A standard panel checks a defined set of recognized causes. Several areas with a supporting evidence base sit outside it.
Half of the picture is your partner's. A standard semen analysis measures count, motility, and shape. It does not measure the integrity of the DNA inside the sperm, which is the paternal factor most consistently associated with miscarriage.
What a Standard Recurrent Miscarriage Workup Misses
After recurrent loss, attention tends to land on the embryo and its genetics. The environment the embryo has to implant into, the uterine lining and its bacterial balance, is rarely examined with the same care. A standard workup may not look at the lining this way at all.
The male partner is often evaluated with a single semen analysis, if at all. The biology that produces that sample, and the DNA integrity inside it, frequently goes unexamined, even though it is directly relevant when an embryo implants but does not continue.
The timing has historically compounded the gap. Waiting for a third loss before a thorough investigation means another pregnancy, another loss, and another round of grief before anyone looks deeper. The 2026 definition update moved that starting line forward.
Nine Tests Often Missing From a Recurrent Miscarriage Workup
Thyroid antibodies and recurrent miscarriage
Thyroid autoimmunity can be present even when TSH reads within range. A 2020 meta-analysis of twenty-two studies found that thyroid peroxidase antibodies were associated with recurrent miscarriage in women whose thyroid function was otherwise normal, with the odds roughly doubled. This is an association rather than a proven cause, and treating the antibodies with thyroid medication has not consistently improved live birth in trials. The point is to recognize the pattern. If your antibodies were never measured, that pattern was never seen.
Antiphospholipid antibodies and recurrent pregnancy loss
Antiphospholipid syndrome is one of the few causes of recurrent loss that every major guideline agrees should be screened for. What matters is how the test is run. A diagnosis requires more than one positive result, repeated about twelve weeks apart. A single test, run once, can miss it or mislabel it. If you were tested one time, or not at all, confirming this was done correctly is a reasonable first step.
Chronic endometritis and implantation
Chronic endometritis is a low grade, often symptomless inflammation of the uterine lining, the surface an embryo has to implant into. It is identified on a biopsy that looks for specific immune cells, not on a standard ultrasound. The 2026 ASRM committee opinion describes a substantial body of evidence linking it to recurrent loss, with studies finding it in anywhere from seven to fifty-seven percent of women with recurrent loss. Most workups do not examine the lining this way.
The vaginal and uterine microbiome
The vaginal and uterine environment has its own bacterial balance. When that balance shifts away from protective Lactobacillus, or when organisms such as Ureaplasma or Mycoplasma are present, implantation and early pregnancy can be affected. Most clinics test here only when there is an obvious symptomatic infection, so quieter imbalances may go unmeasured. This can matter in a donor egg cycle as well. The egg may be someone else's. The environment it implants into is still yours.
Gut health, gluten, and inflammation
Loss is not only a reproductive event. It can also be an inflammatory one. Gut infections, imbalances, and reactions to gluten a person is not aware of can contribute to inflammation that does not stay in the gut. Someone can eat carefully at home and still react to exposure they did not see, in a sauce, in shared flour, when eating out. A comprehensive stool test can read the gut environment, inflammatory markers, and the antibodies that signal exposure. A standard miscarriage workup does not usually include this.
Sperm DNA fragmentation and miscarriage
A standard semen analysis checks count, motility, and shape. It does not measure the integrity of the DNA inside the sperm. A 2012 meta-analysis in Human Reproduction, pooling sixteen studies and nearly three thousand couples, found miscarriage rates rose with sperm DNA damage, with roughly twice the relative risk where damage was high. A 2019 review in Fertility and Sterility focused specifically on recurrent loss and found that male partners had higher sperm DNA fragmentation, on average, than fertile men. The 2026 ASRM guidance notes that sperm DNA fragmentation testing can be considered after otherwise unexplained recurrent loss. The embryo carries two sets of instructions, and after repeated loss only one of them is usually examined.
The male partner's metabolic and hormonal workup
Sperm quality is shaped over the roughly seventy-four days it takes sperm to develop, and the male partner's metabolic and hormonal health is part of that picture. A fuller evaluation may include fasting glucose, HbA1c, insulin, a complete thyroid panel, testosterone, DHEA, ferritin, and inflammatory markers. Most workups stop at the semen analysis, leaving the biology that produces it unexamined.
Blood sugar, insulin, and recurrent loss
Glucose and insulin regulation affect hormone balance, ovulation, and the early environment a pregnancy depends on. These patterns can sit beneath the surface in someone who looks healthy and whose routine labs were called normal. This is an area where the guidance aligns. The 2026 ASRM committee opinion notes that an elevated HbA1c is associated with recurrent loss, and that HbA1c can pick up early shifts a single glucose reading may miss. Well controlled blood sugar is not the concern. Blood sugar drifting upward without anyone watching is. A fuller evaluation looks at fasting insulin and HbA1c, not a single fasting glucose.
The nervous system, cortisol, and progesterone
Recurrent loss can show up in the body. Disrupted sleep, waking between one and three in the morning, and a change in baseline anxiety can reflect HPA axis dysregulation, which in turn can affect progesterone, thyroid conversion, and immune function. Progesterone is often among the first hormones to shift, sometimes before AMH or FSH move, so it is most useful read in the context of the luteal phase and the wider picture rather than as a number on its own. A four point cortisol curve can show this where a single blood draw cannot.
Recurrent Miscarriage Lab Markers and Functional Targets
These are the markers behind the nine areas. Where a number is shown, note the difference between a standard reference range, built to flag disease, and a fertility optimized target. Normal is not always the same as optimal. US units throughout.
| Area | What we look at | Standard range | Fertility optimized target |
|---|---|---|---|
| Thyroid function | TSH | "Normal" to about 4.0 mIU/mL | 0.5 to 2.0 mIU/mL (Fab Fertile functional target) |
| Thyroid function | Free T3 | Often not run | 3.4 to 4.4 pg/mL |
| Thyroid autoimmunity | TPO antibodies | Often skipped when TSH is normal | Presence matters, lower is better |
| Antiphospholipid | aPL panel, repeated about 12 weeks apart | Single test common | Confirmed with repeat testing |
| Uterine lining | Endometrial biopsy for chronic endometritis | Not in standard workup | Plasma cell screen |
| Reproductive microbiome | Vaginal and uterine balance | Tested only when symptomatic | Lactobacillus dominant |
| Iron status | Ferritin | "Fine" at 15 ng/mL | 80 to 100 ng/mL (functional target) |
| Metabolic | Fasting insulin, HbA1c | Single fasting glucose common | Fasting insulin under 5, HbA1c lower normal |
| Male factor | Sperm DNA fragmentation | Not in a standard semen analysis | Measured directly |
Functional targets such as ferritin 80 to 100 are not universal clinic standards. They reflect a fertility optimized range rather than a disease based one.
Functional Fertility Testing vs the Standard Recurrent Miscarriage Workup
A standard recurrent miscarriage workup is designed to identify established medical causes of pregnancy loss and guide evidence based treatment. That is appropriate, and it is not what a functional fertility evaluation replaces.
The difference is scope. A standard evaluation focuses on recognized causes of recurrent miscarriage. A functional fertility evaluation looks more broadly at the systems that influence reproductive health and pregnancy, alongside your reproductive endocrinologist, not instead of one.
What a standard recurrent miscarriage workup covers
A reproductive endocrinologist following the 2024 ASRM evaluation guidance and a functional fertility evaluation begin with many of the same foundations. Both assess for antiphospholipid syndrome, evaluate the uterine cavity, consider parental genetics when indicated, assess thyroid function, and screen for metabolic conditions such as diabetes. Chronic endometritis may be investigated in selected situations, and sperm DNA fragmentation can be considered after unexplained recurrent loss. None of these investigations is fringe. They are supported within current reproductive medicine guidance. Where the approaches differ is what happens after the standard evaluation is complete.
What functional fertility testing adds
Current ASRM and ESHRE guidelines do not recommend routine testing for natural killer (NK) cells, hereditary thrombophilia panels outside specific indications, MTHFR variants, or homocysteine as part of every recurrent miscarriage evaluation. NK cell testing in particular remains controversial within conventional reproductive medicine. A functional fertility evaluation may include these markers because they can provide additional context when interpreted alongside the broader clinical picture.
The emphasis is on patterns rather than isolated results. NK cell activity and antinuclear antibodies are interpreted as possible markers of immune activation, not as independent explanations for pregnancy loss. Homocysteine and MTHFR results are interpreted alongside vitamin B12, folate, and other nutritional markers to individualize nutritional support, rather than as a single cause of miscarriage. The reproductive microbiome, comprehensive stool testing, and functional targets for ferritin and vitamin D are approached the same way. They may identify factors associated with reproductive health, but they are not established diagnostic tests for recurrent miscarriage and should not be interpreted in isolation.
How the gut, blood sugar, and nervous system fit into the picture
Gut health, metabolic function, inflammation, and nervous system regulation do not operate independently. They interact with one another and may influence the physiological environment that supports conception and early pregnancy. Rather than evaluating each system separately, a functional fertility evaluation considers how multiple findings fit together. An individual marker can appear unremarkable on its own but become more meaningful alongside the rest of the picture. None of these findings is presented as a proven cause of miscarriage. They help build a more complete understanding of factors that may be influencing reproductive health.
What testing can and cannot promise
Finding a pattern is not the same as proving a cause, and identifying an abnormal marker does not guarantee that correcting it will improve live birth rates. Treating thyroid antibodies alone has not consistently improved live birth outcomes in clinical trials, and the evidence for treatment strategies in sperm DNA fragmentation continues to evolve. The value of a comprehensive evaluation is not in promising a specific outcome. It is in identifying what has, and has not, been investigated, so that your next decision rests on the fullest picture possible rather than a limited set of results.
Recurrent Miscarriage Success Story: Gayathri and Josh
Gayathri and Josh came to Fab Fertile after two years of trying and multiple early miscarriages. They had already changed their diet and made real lifestyle adjustments, and nothing was holding. What they did not yet have was a full picture of what was driving the losses. When the work was done, seven patterns emerged that had not been fully evaluated: gut infections, food sensitivities, adrenal insufficiency, thyroid imbalance, immune imbalance, circadian rhythm disruption, and emotional stress load. Not a single fix, but an interconnected set of systems, each contributing to an environment that could not sustain a pregnancy. They conceived naturally five months after starting the Fab Fertile Method and now have a daughter.
Watch Gayathri and Josh tell it: https://youtu.be/RClCERlxUE0
Research on Recurrent Miscarriage and Functional Testing
2026 definition change. American Society for Reproductive Medicine, Recurrent Pregnancy Loss: A Committee Opinion, Fertility and Sterility 2026. Two or more losses, not necessarily consecutive, with biochemical losses confirmed by hCG now counted. Replaces the 2012 opinion. https://www.asrm.org/practice-guidance/practice-committee-documents/recurrent-pregnancy-loss-a-committee-opinion-2026/
Standard evaluation. Practice Committee of the American Society for Reproductive Medicine. Evaluation and treatment of recurrent pregnancy loss, updated guidance 2024.
About half of the cases are unexplained after standard evaluation. StatPearls, National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK554460/
Thyroid peroxidase antibodies and recurrent miscarriage in euthyroid women, odds roughly doubled. Meta-analysis of twenty-two studies. https://pubmed.ncbi.nlm.nih.gov/32198952/ Treatment caveat: levothyroxine did not improve live birth in TPO positive euthyroid women (TABLET, New England Journal of Medicine 2019, https://pubmed.ncbi.nlm.nih.gov/30865821/).
Sperm DNA fragmentation and miscarriage. Robinson L, Gallos ID, Conner SJ, et al. Human Reproduction 2012;27(10):2908 to 2917, relative risk 2.16 (95% CI 1.54 to 3.03). https://pubmed.ncbi.nlm.nih.gov/22791753/ Recurrent loss specific: McQueen DB, Zhang J, Robins JC. Fertility and Sterility 2019;112(1):54 to 60. https://pubmed.ncbi.nlm.nih.gov/31056315/
Blood sugar and HbA1c. ASRM 2026 committee opinion, elevated HbA1c associated with recurrent loss. https://www.sciencedirect.com/science/article/abs/pii/S0015028226001275
Frequently Asked Questions About Recurrent Miscarriage Testing
Do I have to wait for three losses before this is worth investigating?
No. As of the 2026 ASRM revision, two losses meet the definition of recurrent pregnancy loss, and they do not have to be consecutive. Biochemical losses count.
My results came back unexplained. Does that mean there is nothing to find?
Not necessarily. Unexplained usually describes how far the workup went. Several areas with a supporting evidence base sit outside a standard panel.
Why test my partner if the losses are happening to me?
Because the embryo carries two sets of instructions. Sperm DNA fragmentation, which a standard semen analysis does not measure, is the paternal factor most consistently associated with miscarriage, and the 2026 guidance notes it can be considered after unexplained recurrent loss.
Does any of this matter if I use donor eggs?
The egg may be someone else's. The lining it implants into, the microbiome, and the inflammatory and metabolic environment are still yours.
Is this instead of my fertility clinic?
No. A functional fertility evaluation works alongside your medical team, reviewing what a standard workup may not have covered so your next decision rests on a fuller picture.
When to Get a Second Opinion on Recurrent Miscarriage
After two or more losses, a cause is found in fewer than half of cases on standard testing. Often that means the evaluation reached the end of the standard panel and stopped. The 2026 guideline moved the starting line forward, so the wait for a third loss is no longer necessary. The evaluation that follows is still only as complete as the questions it asks. If you are reading this and recognize that most of these areas were never looked at, that is the gap a second opinion is meant to close.
A Functional Fertility Second Opinion is a call where I review your labs, your history, your losses, and your partner's results together, in one place. You leave knowing what your results have been signaling and what your next decision could rest on. Whatever you decide afterward is yours, made with information your workup may not have given you.
Book the Second Opinion at https://fabfertile.com/pages/book
Want the nine in writing, with the markers behind each one? Email hello@fabfertile.ca, subject MISSED, for the What Your Clinic Missed guide.
Related Reading
Recurrent Pregnancy Loss: The Functional Fertility Approach. https://fabfertile.com/blogs/learn/recurrent-pregnancy-loss
Male Factor Fertility: The Overlooked Variable in Embryo Outcomes. https://fabfertile.com/blogs/learn/male-factor-fertility
Inflammation and Fertility: The System Nobody Checked. https://fabfertile.com/blogs/learn/inflammation-and-fertility
When Stress Is the Missing Diagnosis: Nervous System Load and Fertility. https://fabfertile.com/blogs/learn/nervous-system-load-fertility
Diminished Ovarian Reserve: The Functional Fertility Approach. https://fabfertile.com/blogs/learn/diminished-ovarian-reserve
About the Host
I'm Sarah Clark, founder of Fab Fertile and host of Get Pregnant Naturally, a podcast with over one million downloads. My functional fertility team works with couples navigating low AMH and failed IVF, reviewing functional lab results, gut microbiome, food sensitivity, vaginal microbiome, nutrigenomics, HTMA, DUTCH, toxin testing, and bloodwork alongside nervous system work, to help identify patterns that may not have been considered. We work alongside your medical team, not instead of them. Subscribe to Get Pregnant Naturally for weekly episodes on fertility optimization, IVF preparation, and the lab work your doctor probably isn't running.
By Sarah Clark, founder of Fab Fertile, host of Get Pregnant Naturally (1M+ downloads), and author of Fabulously Fertile. Last reviewed June 2026.
