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How Your Thyroid Impacts Your Reproductive Health

Nov 03, 2020

By Kasey Willson

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What comes to mind when you think about hormone health? Most women respond with cycle health, periods and moods. That's right, but there is so much more to the function of hormones within your body. If your ears prick up when I say that weight gain, low energy and fertility challenges are also governed by your hormone health, then this episode if for you. 

Let's chat thyroid health. Your thyroid gland is a crucial part of your body’s endocrine system and is found in prime position, at the front of your neck. To paint a picture of what your thyroid gland looks like, close your eyes and imagine a butterfly shaped gland on your neck.

It is something I take extra care of, as a struggling thyroid was a contributing factor to our miscarriage. When I push myself too hard, don't honour my body with the rest it needs, signs of an under active thyroid are the first symptoms I notice. 

Just like your menstrual cycle, thyroid function is also a brain driven event via a feedback loop between your hypothalamus and pituitary gland (in your brain) and your thyroid gland. Through the production of thyroid hormones, your thyroid gland is responsible for regulating processes such as cellular oxygen consumption, basal metabolism, energy production, normal growth and thermogenesis. Your thyroid therefore governs your weight, energy, temperature and reproduction, amongst so much more.


When you have a test for your thyroid function, this will often be limited to just one small portion of the thyroid hormone picture (known as the TSH test). Among TSH, there are other hormones and antibodies which can positively and negatively effect your thyroid function. These include:

  • Thyroid releasing hormone (TRH)
  • Thyroid stimulating hormone (TSH)
  • L-Thyroxine (T4)
  • Triiodothyronine (T3)
  • Reverse T3 (RT3)
  • Thyroid antibodies: Thyroglobulin (TG) and Thyroid Peroxidase (TPO)

TRH regulates the release of TSH by the pituitary gland (in your brain).


Once released by your pituitary gland, TSH stimulates the release of thyroid hormones, T3 and T4. It will increase when the body requires more thyroid hormones and will be decreased when there is abundance, to signal to the body to slow thyroid hormone production.


Produced and released by the thyroid gland, T4 makes up approximately 85% of the thyroid hormone. As T4 is the relatively inactive form of thyroid hormone, small amounts are converted into T3 for the body to use it for important bodily functions.


Majority of the T4 and T3 circulates in your bloodstream bound to a protein. The small percentage which is not bound is referred to as free T4 and free T3.

Free T3 is the most active thyroid hormone, as it can attach to a receptor and govern bodily functions. Some T3 is produced by the thyroid gland and the body also converts 85% of T3 from T4 in tissues such as the liver, muscles and kidneys, in order to activate and energise all of the cells of the body. Free T3 controls your metabolism, energy levels, body temperature, your bowel movements and impacts the health of your adrenal and sex hormones.


When the body is in a state of stress, adrenal imbalance (high or low cortisol production), toxicity and/or nutritional deficiencies, T4 can be converted into the inactive Reverse T3 (RT3), instead of T3.


Thyroid antibodies are a measurement of the body mistakenly attacking your thyroid and include Thyroglobulin (TG) and Thyroid Peroxidase (TPO) antibodies. When inflammation progresses in the body, this creates confusion between normal tissue and foreign invaders. The body starts attacking its own tissues and the symptom of an auto-immune condition develops. Hashimoto's thyroiditis and graves disease are examples of autoimmune conditions of the thyroid gland.

Contributing factors to Thyroperoxidase (TPO) antibodies include:

  • Excess oestrogen conditions, such as pregnancy, taking the oral contraceptive pill and HRT
  • Breast cancer Tamoxifen therapy 
  • Liver diseases

Thyroglobulin (TG) antibodies impact the growth and function of the thyroid gland and are often high in thyroid cancer or Hashimoto's thyroiditis.  


In order for you to have healthy thyroid function, healthy TSH levels, adequate production of T4 hormone and effective conversion into active T3 is required. The conversion of T3 into RT3 must be controlled and thyroid antibodies should be kept at a low level, or even better, non existent. More information about thyroid panel levels to strive for are found in my hormone health book- Balanced, The Natural Way To Healthy Hormones.

Signs and Symptoms of Thyroid Imbalance

  • Fatigue
  • Weight gain
  • Cold intolerance & cold extremities
  • Dry skin or hair
  • Hair loss, or thinning. Read more about overcoming hair loss here.
  • Loss of outer third of eyebrow
  • Constipation
  • Poor concentration
  • Low motivation
  • Depression
  • Apathy
  • Loss of memory
  • Muscle aches, cramps and pain
  • Fluid retention
  • Low heart rate
  • Abnormal cholesterol and triglyceride levels
  • Irregular and heavy periods
  • Infertility and trouble with lactation when breastfeeding
  • Fatigue
  • Weight loss
  • Heat intolerance
  • Increased sweating
  • Frequent bowel movements
  • Poor concentration
  • Anxiety
  • Restless legs
  • Irritability
  • Insomnia
  • Muscle weakness
  • Shortness of breath
  • Heart palpitations
  • High blood pressure
  • Irregular periods
  • Infertility
  • Miscarriage

Effects Of Thyroid Imbalance:


When your thyroid is struggling, this often impacts the production of your sex hormone progesterone. 

The luteal phase (second half of your cycle) is when progesterone should be dominant, peaking around day 21 up to 200 times the levels of oestrogen. Failure for progesterone to peak during the luteal phase, will contribute to oestrogen dominance and the symptoms of PMS. You can learn about oestrogen dominance here.

Low progesterone also contributes an increased release of the hormone aldosterone in your body. Higher aldosterone causes the body to retain salt and therefore leads to the PMS symptom of fluid retention.

An early drop in progesterone in the luteal phase of your cycle and high prolactin levels (the breastfeeding hormone) could also be a major cause of the PMS symptoms of weepiness, paranoia, mood swings and irritability.  In this case, periods could also start suddenly and contain clots. This premature drop in Progesterone is a cause of a luteal phase defect and resulting infertile cycle. 

Your limbic area of your brain, which controls emotions, houses the largest concentration of progesterone receptors in your body and therefore may explains many low progesterone PMS symptoms of emotional outbursts, mood swings, violent urges and uncontrolled rage.


Under active (hypothyroidism), which is seen with a TSH reading over 2.5 on a blood test is left untreated, can lead to miscarriage.1 Both overactive (hyperthyroidism) and under active thyroid function are associated with issues conceiving and the presence of thyroid antibodies in autoimmune thyroid disease, even with healthy TSH levels has been linked with an increased risk of miscarriage.2  

In the early days, weeks and months of pregnancy, thyroxine is critical for your baby's neural and cognitive development3,4 

Testing For Thyroid Function

You can have a thyroid function test performed through your GP however you may come across one of two challenges when asking for a thyroid test.


By merely testing TSH, you cannot accurately determine the function of the thyroid gland and the effects it has on your body. Unfortunately, General Practitioners are under a lot of pressure to meet Medicare guidelines, which prevent them from completing this full thyroid panel (unless the initial TSH result is skewed). In most cases it is not out of the labs reference range.

Ultimately the whole panel of TSH, Free T4, Free T3, RT3 and thyroid antibodies should be included for a comprehensive evaluation of your thyroid health. If your GP is unwilling to run these tests, you can gain a full panel through your naturopath or functional medicine doctor but be prepared to pay the extra (around $180 for the Dunwoody Complete Thyroid Panel), as Medicare and most private health funds will not cover the costs.


Unfortunately, the conventional approach to thyroid treatment is to wait until thyroid function is severely affected before a treatment approach of hormone replacement is given. Reference ranges on blood tests are much larger than optimal ranges and therefore many patients are undiagnosed for under active thyroid function for many months, or even years. A TSH of 1-2 is optimal.

In order to have healthy thyroid function throughout your body, additional to normal TSH readings, the following needs to occur:

  • Adequate production of the T4 hormone
  • Effective conversion of T4 into the active T3
  • Prevention of T4 into dangerous RT3
  • Prevention of the body producing thyroid antibodies.

You can see that by merely testing TSH, you cannot accurately determine the function of the thyroid gland and the effects it has on the body. This may have shone some light on why you may be getting numerous ‘normal’ blood results from your doctor, but experiencing multiple symptoms associated with imbalanced thyroid function.

Another simple test to do at home, is to record your first morning underarm body temperature (after 10 mins of lying flat in bed). If it does not fall between the normal ranges of 36.4 – 36.9 degrees Celsius (most accurately tested between days 2-9 of your menstrual cycle), this is an indication of poor conversion of T4 into active T3.

Causes Of Thyroid Gland Imbalance

Although I delve right into this topic in Balanced, The Natural Way To Healthy Hormones. Here is a brief list of contributing factors of imbalanced thyroid function.

  • Poor gut health & food intolerances, which contribute to issues absorbing nutrients needed for thyroid function, as well as lead to inflammation production. Use of NSAID's and corticosteroids can contribute to this case of a leaky gut.
  • Imbalanced microflora within your gastrointestinal tract is often present together with poor digestion of your foods, absorption of your nutrients and elimination of your wastes.
  • Autoimmune conditions, including coeliac disease. Gluten intolerance and coeliac disease has strong association with the autoimmune thyroid disorder, Hashimoto's thyroiditis.10 Coeliac disease and non-coeliac gluten sensitivity should be ruled out with thyroid imbalance and avoided, especially in the case of raised thyroid antibodies
  • Insulin resistance
  • Long standing chronic and acute infections. Lyme Disease can impact the function of the thyroid gland and contribute to the autoimmune condition Hashimoto's thyroiditis.
  • Vitamin and mineral deficiencies- particularly of those that play a role in thyroid synthesis and conversion- iodine, vitamin A, tyrosine and selenium.

As spoken about in episode 2 and 3, exposure to chlorine and fluoride. both through ingesting, breathing in and absorbing through your skin, contributes to iodine deficiency. These are added into most main water supplies, highlighting the need for a quality water filter for your drinking and bathing water. If you are a swimmer, head over here to gain tips you can use to reduce chlorine exposure when swimming in chlorinated pools.

  • Goitrogen foods, which block thyroid hormone production and function. These include soy, peanuts, millet, pine nuts and uncooked brassica vegetables.
  • Endocrine disrupting toxins, including bisphenol A (BPA) have the potential to disrupt thyroid hormone function.5,6 Exposure to toxic metals, such as cadmium and lead, can impact the metabolism of thyroid hormones7 and perfluoroctanoic acid (PFOA), found in nonstick teflon and gore-tex (waterproofing) products can also negatively effect your thyroid health.8  
  • Another endocrine disrupting toxin PBDE, found in flame retardants, upsets thyroid health by mimicking thyroid hormones.This leads to a decrease in TSH levels and a perceived decreased need for thyroid hormone production.9 

    Exposure to agricultural chemicals (particular organochloride), herbicides, pesticides, household cleaners including toxic ingredients and other chemical exposures can all contribute.

  •  Ongoing emotional, physical, chemical and nutritional stress, will cause your vulnerable adrenal glands to produce high levels of the stress hormone cortisol. When you are stuck in a state of fight or flight, cortisol levels remain higher for longer and this will often lead to weakened thyroid gland function.  


Nourishing Your Under Active Thyroid


As iodine is an integral component of thyroid hormone, adequate levels are critical for healthy thyroid function. Here in the thyroid, iodine is stored (70-80% of the body levels) and used to produce thyroid hormones, Thyroxine (T4) and Triiodothyronine (T3).11 

Healthy iodine status is even more important to reach in your preconception and pregnancy stages of life, as an expecting Mum's production of T4 will increase by 50%. Your baby will receive 50 micrograms a day of iodine through the transfer of thyroxine, which is essential up until weeks 18-20 gestation.12,13,14 At this point your baby will be producing adequate levels of thyroid hormone by themselves. 

The risks of an expecting mum not receiving adequate iodine throughout pregnancy include goitre development, hypothyroidism, hypertension, miscarriage and stillbirth. For the baby, damage is highest within the first 8 weeks of gestation and include brain damage, impaired neurophsychological damage, lower IQ, hypothyroidism, goitre, congenital abnormalities, cretinism, issues with motor skills and hearing.12, 15, 16

These impacts on neurocognition are long term, despite sufficient iodine status throughout childhood. One Tasmanian longitudinal study followed children of mothers who were both iodine replete and iodine deficient during pregnancy. Despite growing up meeting iodine requirements, the 9 year old children were assessed for spelling, grammar and English literacy performance and those whose mothers had a median urinary iodine concentration (MUIC) of <150 micrograms/L (150-249 is adequate) during pregnancy showed a reductions in their performance compared to those whose mothers had MUIC of 150micrograms/L.13


Not only are soils greatly deficient in iodine worldwide, the availability of your body using iodine is also impacted by consumption of goitrogen foods, including soy, millet, peanuts, pine nuts and uncooked brassicas (cabbage, broccoli, brussels sprouts, cauliflower, kale, turnips, mustard greens, radishes, turnips, horseradishes). Once cooked however, the goitrogen properties are no longer an issue for cruciferous veg, for example steaming or stir-frying (in coconut oil). 

Fermenting cabbage on the other hand, actually increases the levels of goitrogens that it contains, however reduces the level of nitriles by half. Nitriles are a more toxic chemical found in cruciferous veg that impacts thyroid health. So if anything fermenting these vegetables (such as sauerkraut and kimchi), has a neutral, to slightly beneficial effect.

The most important thing to be aware of is that if your iodine intake is sufficient, having 1-2 tbsp sauerkraut with meals, along with 3-6 servings of other cooked cruciferous vegetables per week, the goitrogens will not affect your thyroid health. When iodine levels are deficient however, goitrogens will have an impact. Be sure to always cook or ferment these veggies to overcome this issue. 

Iodine deficiency is further exacerbated by frequent exposure to bromide from pesticides (in conventionally farmed produce), plastics (like computers and laptops), breads and other baked goods, soft drinks, medications and fire retardants.

Even after fermentation (into miso, natto, tempeh and tamari), soy products may still disrupt thyroid function, but these options are the safest for overall health if you do reach for soy. Just be sure they are organic and GM free.

Sources of small amounts of iodine include milk, seaweed and iodine fortified foods such as bread and iodised salt. There is seasonal variance of iodine levels in dairy and bread in most cases contains gluten, often soy and Bromide, which as mentioned previously, competes with iodine uptake.

Did you know that an iodine solution used to be used to clean the milk vats? Now this has been replaced with other cleaning solutions- often containing chlorine and therefore presenting further issues with iodine deficiency in the body. 

Seaweeds are a nourishing sea vegetable, naturally high in the mineral iodine. Iodine is crucial for thyroid health, as it is stored in the thyroid and is crucial for the production of thyroid hormone.

You will therefore likely benefit from the addition of seaweeds into your diet. Seaweed types to try include nori, wakame, arame, kelp and dulse. My favourite and to be honest, easiest way of adding seaweed into my day, is by sprinkling dulse flakes into bone broth, soups, salads, or over cooked meals. 1-2 tsp per day is a nourishing amount. I also love using a high quality Himalayan salt that has pulse flakes ground up within- this is my fav.


I step you through the iodine requirements and recommended dosing for preconception and pregnancy in my preconception guide, Path To Glowing Mumma. If you have a history of thyroid antibodies, you will need close monitoring to ensure Thyroid Peroxidase antibodies are not increasing. In this case, iodine supplementation will need to be adjusted. 

The thyroid gland contains some of the highest stores of selenium in the tissues of the body.24 Consider iron, selenium, tyrosine and zinc rich foods and supplements alongside iodine as well, as these work in synergy to support thyroid hormone production and selenium is needed to support the conversion of Thyroxine (T4) into the active form of thyroid hormone (T3) as well as acting as an antioxidant to protect your thyroid against oxidative stress.23 

Thyroid hormones have an important function within the antioxidant system of the body and increased oxidative stress is indicated with thyroid disorders, particularly hypothyroidism. Antioxidant therapies therefore play a big role in treatment of low thyroid function.25 Supplementation of antioxidant rich vitamin E provides much needed protection against oxidative stress in hypothyroidism, as does the antioxidant N-acetyl cysteine, among liver and blood sugar support.

The amino acid Tyrosine is rich in protein rich foods such as meats and cheese and selenium is highest in Brazil nuts and fish.

Magnesium supplementation is key in hypothyroidism, to provide blood sugar balance, energy support, and easing of aches and pains symptoms. My fav way of adding in extra magnesium, is through Magnesium chloride bath salt foot soaks, or spraying on the oil before bed. 

In the case of autoimmunity of your thyroid, selenium can help reduce the antibody production and vitamin D plays a key role as well.19 Medicinal mushrooms such as reishi and shiitake along with herbs echinacea, rehmannia, hemidesmus, calendula and pau d'arco help to modulate the overactive immune system.

Your thyroid also requires more vitamin A than any other organ and gland and therefore healthy levels are crucial for thyroid health. A deficiency in vitamin A is associated with iodine deficiency and increasing intake of vitamin A has shown improvements in iodine status and thyroid function.  Cod liver oil, egg yolks and liver pate are my fav ways of delivering vitamin A through my diet. You can try my vitamin A rich liver pate over here.

The carbohydrate Inositol also plays a role in the first steps of thyroid production by supporting TSH receptor activity17 and can be found in beans, brown rice brewers yeast, citrus fruits and rock melon. 

Other Ways To Support Your Thyroid Health


Eliminate gluten (particularly glyphosate sprayed wheat) and other foods that contribute to inflammation in your body, as this is a cause of autoimmunity and thyroid antibody production. Examples include refined sugar, caffeine, alcohol and industrial seed oils. Also consider having a food intolerance test performed to check for additional individual inflammatory foods in your diet. Reducing inflammation will improve overall hormone health, including the way you both look and feel- less puffy, lowered pain, sharper brain function and increased energy.

Refined sugar, wheat and wheat products will also increase your blood sugar levels and contribute to insulin resistance over time. Every time your blood sugar and insulin levels are increased, this puts pressure on your vulnerable adrenal glands, which are integral for the health of the thyroid. Want more tips for supporting your adrenals? Read this one.

Using coconut oil in place of vegetable and seed oils for cooking will not only reduce inflammation as this is a stable oil to heat, but coconut oil directly supports your thyroid function. Your body converts the oil straight into energy, bypassing the liver and therefore avoiding stress on the digestive organs.

Leave your weight worries in relation to the coconut oil use behind, as it has thermogenic properties which actually stimulate your metabolism. Coconut is also immune protective, so if you’re struggling with the auto-immune condition of Hashimoto's Thyroiditis, it may also be beneficial for you.

Cook with this oil, add into recipes such as smoothies, or if you don’t mind the taste, take straight off the spoon when you’re in need of a natural pick-me-up.


Vitamin B5 can help produce hormones that counteract the stress response. The amino acid Tyrosine also supports your adrenal glands, by acting as a precursor to epinephrine,18 as well as neurotransmitters which support promote a balanced nervous system function such as dopamine and norepinephrine. Vitamin B6 has a similar action19 and vitamins B1, B12 and inositol also play a role in healthy nervous system function.20  

The herb withania (ashwaganda) is helpful in circumstances of debilitating physical and mental health, stress and anxiety, due to its rejuvenating and adaptogenic properties that help your body adapt to stressful situations.21,22  Liquorice and rehmannia also provide adrenal restorative actions. 


Herbal thyroid stimulants include coleus for weight loss support, and bladderwrack to supply iodine and encourage overall thyroid function. The herb gymnema is a good addition for overcoming sweet cravings and effects and restorative effects on your pancreas for blood sugar balancing.

Essential oils contain precious compounds (from the plant they are extracted from), which may also provide you with endocrine balancing effects. I’ve found a combination of applying essential oils topically (to the thyroid, chest, back of neck, lower abdomen, hands and feet) twice daily along with diffusing regularly, to help out a struggling thyroid gland. Head here to download my recommendations of essential oils for your thyroid gland function. 

Consider Your Thyroid

If you're noticing hormone imbalance signs and symptoms, you're having fertility challenges, just feeling flat, or your weight is not budging, consider your thyroid. Ask for a full thyroid panel to be tested from your GP or Integrative GP to detect any thyroid imbalance and ask for copies.

Seek the support of your Naturopath to understand the causative factors behind your thyroid disorder and support areas of imbalances, with foods, nutritional and herbal medicine along with healthy movement and stress reducing practises. 

For my additional thyroid health support, supporting your endocrine system in a holistic way, see my hormone health book, Balanced The Natural Way To Healthy Hormones, available across in the show notes.

If you're looking at bringing a baby into the world, see my preconception support within my guide, Path To Glowing Mumma.


1) Australian Institute of Health and Welfare (AIHW). Australia's mothers and babies, 2013: in brief. Perinatal Statistics Series no.31. Cat no. PER 72. Canberra: AIHW; 2015.

2) Australian Health Ministers' Conference. National Maternity Services Plan 2010. Canberra; 2010.

8) Shrestha S1, Bloom MS2, Yucel R1, Seegal RF3, Wu Q3, Kannan K3,et al. Perfluoroalkyl substances and thyroid function in older adults. Environ Int. 2015 Feb;75:206-14. doi: 10.1016/j.envint.2014.11.018. Epub 2014 Dec 5.

15) Braun L, Cohen M. Herbs and Natural supplements:an evidence-based guide. 4th ed. Sydney:Elsevier; 2015. 



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