Lately, I've noticed an interesting pattern in my fertility practice.

Mold keeps showing up.

Not in every patient. And certainly not as the explanation for every fertility struggle.

But in several of the more complex fertility cases I've been working with, mold and mycotoxin exposure have turned out to be another piece of the puzzle that we didn't discover until we looked deeper.


In fact, mold exposure has been identified in three of my patients who are currently pregnant. In two of those cases, pregnancy occurred after we uncovered the exposure and incorporated a targeted mold protocol into the broader work we were already doing.


Does that mean mold was the reason they weren't getting pregnant? No.

And does it mean completing a mold detox caused their pregnancies? We can't say that either.

Fertility is far too complex for that.

But when I see the same pattern appearing in multiple patients, I pay attention.

And it brings me back to one of the things I love most about functional medicine: When the body isn't responding the way we expect, we keep asking why.


I Don't Start With Mold Testing

One thing I want to make very clear is that mold testing is not where I typically begin with a fertility patient.

I believe we first need to understand the foundations.

Before looking for more complicated explanations, I want to know:


  • Are you ovulating?
  • Are you producing adequate progesterone after ovulation?
  • What does your thyroid function look like?
  • Is insulin resistance or poor glucose regulation present?
  • Are inflammatory markers elevated?
  • Are there important nutrient deficiencies?
  • Is your body getting the raw materials it needs to produce hormones?
  • Are there signs of metabolic dysfunction?
  • And when appropriate, what is happening with sperm health?


These are some of the fundamental systems that influence reproductive health.

And very often, we find things here that need attention.


Maybe thyroid function isn't optimal.

Maybe insulin is higher than expected despite a "normal" glucose.

Maybe vitamin D, iron, B vitamins, or other nutrients need support.

Maybe ovulation is occurring, but the luteal phase isn't functioning as well as we'd like.

We address those things first.

Reveal the foundational imbalances. Address what we find. Give the body time to respond.

But sometimes we do all of that, and something still doesn't make sense.


What Happens When the Numbers Improve...But Fertility Doesn't?

This is where functional medicine gets especially interesting.

Sometimes we've spent months rebuilding the foundations.

Nutrition is better.

Blood sugar regulation has improved.

Nutrient levels are being restored. 

Thyroid markers are moving in the right direction.

Inflammation is improving.

The couple is doing so many of the "right" things.

And yet conception still isn't happening.

Or perhaps there have been repeated pregnancy losses.

Or a biomarker simply refuses to move despite addressing the obvious reasons it should be abnormal.


That's when I start asking:

What else could be placing a burden on this body?

And that's when we may begin looking deeper.

Depending on the individual, that can include environmental toxins, mold and mycotoxins, gut health, immune dysfunction, genetics, chronic infections, or other less obvious stressors.

It's not about ordering every functional medicine test available.

It's about following the clues.


Mold Is One of Those Clues I'm Paying More Attention To

Mold is a type of fungus that grows particularly well in damp or water-damaged environments.

But when we're talking about mold and health, we're not only talking about visible mold growing on a wall.

Certain fungi can produce compounds called mycotoxins. Exposure can occur through contaminated foods as well as environmental sources, and researchers have become increasingly interested in the potential effects of certain mycotoxins on endocrine, immune, metabolic, and reproductive health. This is an important distinction because the research does not currently support saying that household mold is a common established cause of infertility. What it does tell us is that certain mycotoxins have biological effects that  make their relationship with reproductive health worth investigating.


What Does the Research Say About Mycotoxins and Fertility?

The research is still developing, particularly in humans, but several potential mechanisms have emerged.


1. Oxidative Stress

One of the most interesting areas involves oxidative stress.

Our reproductive cells are particularly sensitive to the balance between free radicals and antioxidant defenses.

Excessive oxidative stress can affect cellular function, including the environment in which eggs and sperm develop.

And we're beginning to see evidence of this in humans.

A recent study examined follicular fluid from women undergoing fertility treatment and detected several common mycotoxins. Higher levels of certain mycotoxins were associated with changes in oxidative-stress markers and antioxidant activity within the follicular environment.

The researchers also observed relationships with hormones including estradiol, cortisol, and AMH.

That doesn't prove that the mycotoxins caused infertility.

But finding these compounds inside the environment surrounding the developing egg makes this an area of reproductive research worth watching closely.


2. Hormone Signaling

Certain mycotoxins can also behave as endocrine-disrupting compounds.

One of the best studied is zearalenone (ZEN), a mycotoxin with estrogen-like activity.

Experimental research suggests that zearalenone and related compounds can interact with estrogen signaling and potentially influence ovarian function, follicular development, and reproductive hormone pathways.

A systematic review examining these compounds found fairly consistent reproductive effects in experimental and animal studies, including changes in ovarian follicles and reproductive cycling.


However, researchers also noted an important limitation:

High-quality human fertility data are still lacking.

So this is biologically plausible, but we shouldn't turn plausible mechanisms into certainty.


3. Egg and Embryo Development

Experimental studies have also raised questions about the effects of several mycotoxins on:

  • oocyte maturation
  • ovarian follicle development
  • granulosa cell function
  • cellular energy production
  • DNA stability
  • embryo development


A 2025 review of mycotoxin reproductive toxicity described effects involving oxidative stress, genomic stability, cellular structures within the oocyte, endocrine signaling, and embryo development.

Again, much of this evidence comes from animal and laboratory models.

But collectively, it gives researchers several reasons to continue studying mycotoxin exposure in human fertility.


4. Sperm Health Matters Too

This is not just a female fertility conversation.

Research has also investigated mycotoxins and male reproductive health.

Experimental studies suggest certain mycotoxins may interfere with steroid hormone production, increase oxidative stress, and negatively influence spermatogenesis and sperm quality.

Human evidence is still much more limited than I would like it to be, but it reinforces something I say constantly in my practice:

Fertility is a couple's health issue—not simply a woman's health issue.

When we're investigating unexplained infertility, we need to look at both partners.


5. Pregnancy and Pregnancy Loss

This area requires particular caution.

Some studies have found associations between maternal exposure to certain mycotoxins and adverse pregnancy outcomes.

A systematic review of human studies found some evidence linking particular exposures with impaired fetal growth and other pregnancy complications, while evidence for outcomes such as preterm birth and pregnancy loss was inconsistent or limited.


So I would never tell someone: "Mold causes miscarriage." We simply don't have the evidence to make that statement.


What we can say is that environmental exposures are one part of reproductive health that deserves consideration, particularly when someone has experienced recurrent pregnancy loss or unexplained infertility and the more established causes have already been evaluated.


Why Would Environmental Burden Matter Before Pregnancy?

I often explain fertility using the idea of total burden.

Your body isn't experiencing your thyroid, nutrients, blood sugar, gut, stress, immune system, and environmental exposures in separate little boxes.

They're interacting all the time.

Someone may have: a few nutrient deficiencies + insulin resistance + thyroid dysfunction + chronic inflammation + environmental exposures.

None of those necessarily explains the entire fertility picture by itself.

But together?

They may create a physiological environment that isn't functioning optimally.

That's why my goal isn't to find one villain.  It's to identify the layers we can actually change.

We start with the biggest foundational pieces first. Then we reassess.

And if the body still isn't responding the way I would expect, we keep looking.


When Do I Start Thinking About Mold?

I don't believe every person trying to conceive needs a mycotoxin test.

But it moves higher on my list when someone's history includes things like:

  • Known or suspected exposure to a water-damaged building
  • A persistent musty smell or visible mold at home or work
  • Previous significant water leaks, flooding, or water damage
  • Symptoms that appeared or worsened after moving into a particular building
  • Unexplained or persistent inflammatory symptoms
  • Biomarkers that aren't improving as expected despite targeted intervention
  • Unexplained infertility after the foundational factors have been evaluated
  • Recurrent pregnancy loss after appropriate conventional evaluation
  • A health journey where we simply have the sense that another layer hasn't been uncovered yet


None of those symptoms or circumstances proves mold is responsible. They simply tell me whether it might be reasonable to investigate further.


My Recent Patients Have Changed the Way I Think About This

This is probably the biggest reason I wanted to write this article.

I've had the privilege of celebrating several pregnancies recently.

And when I looked back at those fertility journeys, I realized that mold had been uncovered in two out of three of them.


For two of those patients, we had already done substantial foundational work.

We weren't jumping immediately to mold. We had addressed other imbalances first. We had worked on nutrition, metabolic health, hormones, and the individual issues showing up in their testing.

They had already been through multiple phases of support. But something was still missing. Eventually, their histories and lack of expected progress led us deeper. We uncovered mold/mycotoxin exposure and addressed it as another layer of their individualized plans. And afterward, both conceived. 


I want to be extremely careful with how I interpret that.

Those pregnancies don't prove that mold was preventing conception, and they don't prove that a mold protocol caused pregnancy.

There were many interventions, many months of work, and many biological factors involved.

But those experiences have absolutely made me more aware of environmental exposure as a potential missing piece in complex fertility cases. Sometimes the value of clinical experience isn't that it gives us an answer.

Sometimes it tells us which question we should be asking next.

This Is What "Root Cause" Fertility Care Means to Me. Root-cause medicine sometimes gets presented as though there's one hidden diagnosis waiting to be discovered.

That's rarely what I see.

Instead, I see layers. 

Maybe the first layer is insulin resistance.  Underneath that is nutrient depletion.  Then we discover thyroid dysfunction.

We correct those things and reassess.

And occasionally, underneath all of that, there's another stressor, environmental exposure, gut dysfunction, immune activation, genetics, or something else we couldn't see from the beginning.

We reveal one layer, address it, and then listen to what the body tells us next.

That's why I don't believe everyone needs every test on day one.

Good functional medicine isn't about testing everything.

It's about knowing when to look deeper.


If You're Struggling to Conceive, Start With the Foundations

If you've read this and are now wondering whether you should immediately test yourself for mold, that's actually not my biggest takeaway. Start with what we know matters.

  • Understand your ovulation.
  • Look comprehensively at thyroid function.
  • Assess metabolic health and insulin.
  • Evaluate inflammation.
  • Check important nutrient markers.
  • Look at the male side of the equation.
  • Build the foundation first.

And if you've done those things, and something still isn't adding up? Keep asking questions.

Mold may be one possibility.

It may not be yours.

But particularly with unexplained infertility or recurrent pregnancy loss, I don't want to assume we've reached the end of the investigation simply because the standard workup says everything looks "normal." Sometimes there is another layer.

And sometimes, turning over that next stone is exactly where we find the information we've been missing.


A Note About the Research

Research connecting mycotoxin exposure directly with human infertility is still emerging. Much of our understanding of reproductive mechanisms comes from laboratory and animal research, with a smaller but growing body of human evidence.

Mycotoxin exposure should therefore be viewed as one potential environmental factor within a much larger fertility picture, not as a proven explanation for infertility or pregnancy loss. If you're concerned about mold exposure, both the source of exposure and your overall health history should be evaluated rather than assuming symptoms are caused by mold alone.



References

Fucic A, et al. Impact of Fusarium-Derived Mycoestrogens on Female Reproduction: A Systematic Review. Toxins. 2021.

Sun S, et al. Mycotoxin toxicity and its alleviation strategy on female mammalian reproduction and fertility. 2025.

El Khoury D, Fayjaloun S, Nassar M, Sahakian J, Aad PY. Updates on the Effect of Mycotoxins on Male Reproductive Efficiency in Mammals. Toxins. 2019.

Chiminelli I, Spicer LJ, Maylem ERS, Caloni F. Emerging mycotoxins and reproductive effects in animals: A short review. Journal of Applied Toxicology. 2022.

Maternal mycotoxin exposure and adverse pregnancy outcomes: a systematic review. 2020.

Mycotoxin-Induced Oxidative Stress and Its Impact on Human Folliculogenesis: Examining the Link to Reproductive Health. 2025.


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