Trying to Conceive with Hashimoto’s? 3 Diet Mistakes That Could Be Affecting Your Fertility
If you’ve seen your doctor about your Hashimoto’s and fertility, it may have gone something like this.
A short appointment.
A quick look at your thyroid-stimulating hormone (TSH).
A prescription for thyroxine.
“Let’s recheck in three months.”
But if you’re still not conceiving, or you’ve experienced early pregnancy losses, you already know it’s not that simple.
When it comes to Hashimoto’s and fertility, we need to look beyond TSH alone. Thyroid hormones don’t just “support” fertility. They regulate ovulation, influence egg development, support implantation, and are critical in early pregnancy.
Even mild thyroid dysfunction or positive thyroid antibodies can quietly affect outcomes.
Research shows that women who are positive for anti‑thyroid antibodies have around a threefold higher risk of miscarriage and a twofold higher risk of preterm birth, even when TSH is in the normal range.
If you’re preparing for IVF or ICSI, this becomes even more important.
In this blog, I share three common diet-related pitfalls I often see that can impact thyroid function and fertility.
Why Hashimoto’s And Fertility Are So Closely Linked
Hashimoto’s is an autoimmune condition where your immune system attacks the thyroid gland. Over time, this can reduce thyroid hormone production and cause fluctuations in TSH levels.
Thyroid hormones influence:
- Follicle development
- Ovulation regularity
- Luteal phase stability
- Implantation
- Early embryo development
- Miscarriage risk
Even “borderline” dysfunction can affect these processes.
If you’re moving toward IVF, thyroid stability becomes even more critical. Mild TSH shifts have been associated with lower success rates and increased early pregnancy loss.
Now let’s look at the three most common nutrition mistakes.
Mistake 1: Quitting Gluten Without Proper Coeliac Testing
Gluten is often the first thing commonly removed after a Hashimoto’s diagnosis. But doing this without proper testing can actually create problems.
The Hashimoto’s and Coeliac Connection
Hashimoto’s is the most dominant thyroid subtype found in individuals with biopsy-confirmed Coeliac disease. These two autoimmune conditions frequently co-occur.
Studies suggest that individuals with Hashimoto’s (autoimmune thyroiditis) have roughly a 4–6% risk of also having Coeliac disease, compared with about 1% in the general population.
Why This Matters for Fertility
Untreated coeliac disease is associated with:
- Subfertility
- Increased miscarriage risk
- Adverse pregnancy outcomes
- Nutrient malabsorption
When Coeliac disease goes undiagnosed, intestinal damage can impair the absorption of:
- Iron
- Folate
- Vitamin D
- Zinc
- Selenium
These nutrients are foundational for ovulation, egg quality, implantation, and early embryo development.
It’s crucial not to eliminate gluten before undergoing testing. Consult your doctor about screening for Coeliac serology antibodies.
If you’re already on a gluten-free diet, consider discussing HLA-DQ2/DQ8 genetic testing. While it isn’t solely diagnostic, it can help assess your risk.
If Coeliac disease is confirmed through biopsy (regarded as the gold standard), adhering to a strict gluten-free diet can greatly enhance fertility outcomes.
This is not merely about following dietary trends; it’s about obtaining an accurate diagnosis.
Mistake 2: Ignoring Iodine Balance
Iodine is crucial for the production of thyroid hormones, but daily intake, whether from diet or supplements, must be carefully reviewed.
Too Little Iodine
- Impairs thyroid hormone production
- Affects ovulation
- May reduce implantation potential
Too Much Iodine
Recent reviews show that excess iodine intake can worsen thyroid autoimmunity and increase thyroid peroxidase (TPO) antibodies.
High iodine intake can cause thyroid levels to swing between overactive and underactive states. These fluctuations can destabilise your cycle and impact IVF outcomes.
Most Australian prenatal multivitamin supplements contain between 150 and 270 micrograms of iodine.
That is appropriate for the general population.
But for individuals with Hashimoto’s, an in-depth nutrition assessment is essential.
What To Do Instead
- Review your total iodine intake from supplements and food
- Check your full thyroid panel if it has been more than six months
- Work with a fertility dietitian to develop a personalised nutrition and supplement regimen
Our goal is to find the “Goldilocks zone.” Just right for your thyroid and to support a healthy pregnancy.
Mistake 3: Eliminating Dairy Without Assessing Lactose Intolerance
You may have heard that dairy “causes inflammation” and should be avoided in Hashimoto’s. The evidence tells a more nuanced story.
Does Dairy Worsen Thyroid Antibodies?
A systematic review found that cutting out lactose improved TSH and thyroid antibody levels only in individuals with Hashimoto’s who had confirmed lactose intolerance or other gut inflammation issues.
Why This Matters for Fertility
Individuals with Hashimoto’s and lactose intolerance may:
- Require higher doses of thyroxine
- Experience unstable TSH
- Have reduced medication absorption
Unstable thyroid levels can indirectly affect ovulation, energy, and implantation.
What You Can Do
1. Test for Lactose Intolerance
If you notice persistent bloating, gas, or changes in your bowel habits after consuming milk or dairy, talk to your doctor about being tested for lactose intolerance.
2. Trial a Structured 4-Week Lactose-Free Swap
Switch to lactose-free options while ensuring adequate intake of calcium, iodine, and protein.
3. Separate Medication and Dairy
Never take thyroxine with dairy. Wait at least 2 to 4 hours before consuming milk, yoghurt, or cheese.
4. Monitor Bloods
Recheck TSH and antibodies after dietary adjustments.
Again, this is not about blindly removing food groups. It’s always best to consult a fertility dietitian before changing your diet and supplement intake.
Bottom Line
When managing Hashimoto’s and fertility, here are the three key takeaways:
- Test before removing gluten. Undiagnosed coeliac disease can impair nutrient absorption and fertility.
- Balance iodine intake carefully. More is not better when autoimmunity is involved.
- Assess lactose intolerance properly. Dairy is not the enemy, but malabsorption can destabilise thyroid levels.
If you’re preparing for pregnancy, the right nutrition strategy can help stabilise thyroid hormones, reduce inflammation, and create a more supportive environment for conception.
