Thyroid Health, Hashimoto’s & Pregnancy: What You Need to Know Before and During Pregnancy
Planning a pregnancy with Hashimoto’s disease or hypothyroidism? Here’s what you need to know about thyroid health, fertility, pregnancy, testing, nutrition and lifestyle support. If you've been diagnosed with Hashimoto's or hypothyroidism, you may feel a little apprehensive when it comes to trying to conceive or growing your family.
And that's completely understandable.
Thyroid health and pregnancy are closely connected, and pregnancy places additional demands on your thyroid. But having a thyroid condition doesn't mean you can't have a healthy pregnancy. The key is understanding your thyroid health, preparing where possible before conception, and making sure your thyroid is appropriately monitored throughout pregnancy.
Let's take a look at what you need to know.
Why is your thyroid so important during pregnancy?
Your thyroid plays an important role in your overall health, and pregnancy creates significant physiological changes and increased demands on the thyroid. This becomes particularly relevant if you have Hashimoto's, where your immune system produces antibodies that target the thyroid.
The two main thyroid antibodies are:
Thyroid peroxidase antibodies (TPOAb)
Thyroglobulin antibodies (TgAb)
Thyroid autoimmunity can have effects beyond thyroid hormone levels and has been associated with reproductive concerns including:
Fertility difficulties
Changes in ovulation
Effects on oestrogen activity
Early pregnancy loss
Pre-eclampsia
Preterm birth
Thyroid dysfunction during pregnancy can also affect foetal development. So while thyroid health is important throughout your life, preconception and pregnancy are particularly important times to pay attention to it.
Hashimoto's and fertility: why preconception care matters
One of the things that can be frustrating about thyroid health is that everything can appear "normal" on a basic thyroid test, while there may still be more to investigate.
Thyroid antibodies can sometimes be present before obvious thyroid hormone disruption occurs.
This means thyroid autoimmunity may be relevant even before someone develops obvious thyroid dysfunction. Research has identified associations between thyroid autoimmunity and reproductive concerns, including fertility difficulties, ovulation, early pregnancy loss, PMOS/PCOS, premature ovarian insufficiency and endometriosis.
This is particularly worth considering if you're:
Trying to conceive
Preparing for pregnancy
Experiencing fertility difficulties
Undergoing IVF or assisted reproductive treatment
Experiencing recurrent or unexplained pregnancy loss
Don't wait until you're pregnant to start thinking about your thyroid.
If pregnancy is on your radar, preconception is an ideal time to assess your thyroid health and address any concerns.
What should you actually test?
This is an important one. TSH is an important test marker, but it doesn't tell you the whole story.
TSH reflects the communication from your brain to your thyroid, essentially telling your thyroid to make more or less thyroid hormone. However, it isn’t actually checking the hormones the thyroid actually produces or other factors impacting thyroid function and health.
For example, T4 needs to be converted into active T3 for thyroid function to work properly. Reverse T3 can also influence the picture, particularly during periods of stress.
And then there are thyroid antibodies. Thyroid antibodies can be present before obvious thyroid hormone disruption occurs and can contribute to autoimmune thyroid disease and damage to the thyroid over time.
This is why, particularly when fertility or pregnancy is a priority, looking beyond TSH is worthwhile.
Thyroid-specific tests I look at usually include:
TSH
T4
T3
Reverse T3
TPO antibodies
Thyroglobulin antibodies (TgAb)
Nutrient status’ for iodine and selenium
The appropriate tests will depend on your individual history, symptoms and circumstances, so discuss these with your healthcare practitioner.
Pregnancy is your thyroid's greatest stress test
Pregnancy itself can affect how your thyroid functions.There are significant changes occurring throughout pregnancy, including:
Increased iodine losses through the kidneys
Increased proteins that carry thyroid hormones
Increased production of thyroid hormones
Thyroid-stimulating effects from the hormone hCG
These changes mean thyroid testing during pregnancy needs to be interpreted in the context of pregnancy rather than simply using the same expectations as outside pregnancy. And if you already have Hashimoto's, your thyroid is managing these increased demands while also dealing with an autoimmune process. This is
The first trimester is particularly important
Your baby's thyroid does not develop until approximately 12 weeks. Until then, your thyroid is providing the thyroid hormones needed during this early stage of your baby's development.So once you discover you're pregnant, it's worth discussing thyroid testing with your healthcare practitioner promptly.
A commonly used monitoring approach is:
First trimester: approximately every 4 weeks
Second & third trimester: approximately every 6–8 weeks
Your healthcare practitioner may recommend a different schedule depending on your individual circumstances.
And don't panic over a low TSH alone.
Around 5% of women have a TSH below 0.1 mIU/L by week 11 of pregnancy. This is why looking at the broader thyroid picture — including T3 and T4 — is important rather than interpreting one result in isolation.
What can you do to support your thyroid naturally?
There are plenty of things you can focus on day-to-day that support your overall health alongside appropriate medical management. And importantly, you don't need to do everything perfectly.
1. Eat a nutrient-dense diet
This can be particularly challenging during the first trimester when nausea, morning sickness and food aversions can make eating well feel like a full-time job. Do the best you can.
A simple approach is to aim for five smaller meals throughout the day, including protein with each.
Try to include:
Protein
Fresh fruit and vegetables
Complex carbohydrates
Healthy fats
Eating a good amount of protein may also help reduce feelings of nausea. Think nourishing and balanced rather than perfect.
2. Don't fear carbohydrates
Carbohydrates don't need to be eliminated in an attempt to support thyroid health. The focus is on a moderate carbohydrate intake and quality (and variety) over quantity. Too little carbohydrate can put stress on the thyroid and increase the risk of low thyroid hormones, while too much may be problematic if you're tending towards an overactive thyroid or gestational diabetes.
Good options to focus on include:
Fruit
Vegetables
Wholegrains
Beans
Legumes
3. Keep your blood sugar balanced
Balanced meals can help support steady energy and appetite, while also influencing stress and thyroid hormones.An easy way to build your meals is:
Protein + healthy fats + colourful fruit & vegetables + complex carbohydrates
It doesn't need to be complicated.
4. Don't neglect stress
Yes, I know — stress gets mentioned everywhere!
But it's worth mentioning here too. Chronic stress can affect thyroid function, and pregnancy is already a significant physiological and emotional transition. Rather than waiting until you're pregnant and overwhelmed, start developing stress-management strategies during preconception if you can.
This could be:
Time outdoors
Gentle movement
Meditation
Yoga
Breathing exercises
Quiet time
Time away from screens
The best strategy is the one you can actually stick with.
5. Prioritise sleep and rest
Fatigue is common with both pregnancy and Hashimoto's. Rather than constantly trying to push through it, look for opportunities to rest and recharge. This includes prioritising sleep quality and quantity wherever possible. And remember, rest can look different for everyone.
It might mean:
Physical rest: sleep or a nap
Mental rest: putting your phone away and reading a book
Sensory rest: sitting somewhere quiet or having a relaxing bath
Spiritual rest: meditation, yoga or prayer
You don't have to earn your rest.
6. Look at gut health and inflammation
For some women, supporting thyroid health means looking beyond the thyroid itself. Depending on your individual circumstances, this may involve looking at:
Food intolerances and potential triggering compounds such as gluten
Gut microbiome health
Sources of inflammation elsewhere in the body
Other health conditions
Chronic injuries
Environmental and household pollutants or toxicants
This is not a one-size-fits-all approach. The appropriate strategy depends on your individual health, history and potential drivers of your thyroid concerns.
What if you've had postpartum thyroiditis before?
If you've experienced thyroid concerns following a previous pregnancy, it's worth thinking about your next pregnancy before you conceive. Preconception is an opportunity to focus on all the areas mentioned above to ultimately identify, support and where possible, rectify these issues and concerns. Rather than waiting until pregnancy places additional demands on your body, you can use the months beforehand to create a stronger foundation.
Your thyroid & pregnancy checklist
If you're planning a pregnancy and have Hashimoto's, hypothyroidism or thyroid antibodies, consider discussing the following with your healthcare team:
☐ Thyroid function testing
☐ Thyroid antibody testing
☐ Iodine status and requirements
☐ Nutritional status
☐ Your diet and protein intake
☐ Medications and supplements
☐ Digestive or other health concerns
☐ Stress and sleep
☐ A plan for thyroid monitoring once pregnant
The most important takeaway?
Don't wait until something goes wrong to start paying attention to your thyroid.
If you're planning a pregnancy, preconception is a valuable time to understand your thyroid health and identify areas that may need attention. And if you're already pregnant, it's not too late. Work with your healthcare team to ensure your thyroid is appropriately monitored and managed, while also supporting your nutrition, stress, sleep and overall health. Because thyroid health isn't just about a number on a blood test.
It's about understanding the whole picture.
A final note…
At Nest & Nourish Naturopathy, we believe women deserve to understand what is happening in their bodies — particularly during the important seasons of preconception, fertility, pregnancy, postpartum and beyond.
If you have Hashimoto's, hypothyroidism, thyroid antibodies or concerns about your thyroid and fertility, book an appointment today and let’s work together to help you understand what is happening with you and your thyroid and what can be done.
This article is for general educational purposes only and does not replace individual medical advice, diagnosis or treatment. If you are pregnant or planning pregnancy, ensure your thyroid is appropriately monitored and managed with your healthcare team.