If you’ve been trying to get pregnant without success, your thyroid gland could be to blame. Thyroid health is extremely important when it comes to fertility and reproduction. If your thyroid gland isn’t working properly, it can have a significant impact on your ability to get pregnant, the health of your pregnancy and the health of your baby.
Thyroid dysfunction is one of the most common hormonal disorders affecting women of reproductive age. But despite this, the link between thyroid function and fertility is NOT well known, even amongst some doctors. It’s an issue that comes up time and again with my clients and I suspect that it’s an undiagnosed factor in many cases of unexplained infertility.
What is your thyroid gland?
Your thyroid is a butterfly shaped gland that sits at the base of your neck, in front of your windpipe. Its job is to make and release thyroid hormones into your bloodstream – primarily T4 (thyroxine) and T3 (Triiodothyronine).
These hormones are made from the amino acid tyrosine and the mineral iodine, which you get from your food. Their names come from the number of iodine atoms they contain. T4 contains 4 atoms of iodine and T3 contains 3 atoms.
T3 is the ‘biologically active’ form of thyroid hormone and does the actual ‘work’ in your body’s cells. T4 acts like a storage hormone and only becomes effective once it’s converted into T3 inside your cells.
T3 affects almost every cell in your body. Its primary role is to regulate your metabolism – that is, the rate at which you produce energy (and heat) from the food you eat and the air you breathe. It also has a key role in growth and development, especially brain development.
In order for your body to function normally, your thyroid gland needs to produce the right amount of thyroid hormone. If too much thyroid hormone is produced, your cells end up working too fast and your body goes into ‘overdrive’. If not enough thyroid hormone is produced, your cells work too slowly and your body processes become sluggish.
Thyroid disorders affecting fertility
If you’re struggling to get pregnant, you have a higher chance of having a thyroid disorder.
Thyroid disorders that affect fertility can be classified into 3 main types:
- thyroid autoantibodies (with normal thyroid function)
Hypothyroidism is when the thyroid gland doesn’t make enough thyroid hormone
Hyperthyroidism is when the thyroid gland makes too much thyroid hormone
Thyroid autoantibodies are antibodies made by your immune system, which attack your thyroid gland.
I’ve discussed these 3 conditions in more detail below, along with the symptoms you might experience and how fertility and reproductive health can be affected.
Hypothyroidism is the most common type of thyroid dysfunction. It occurs when the thyroid gland doesn’t make enough thyroid hormone (T4 and T3), causing the body’s processes to slow down.
There are a number of different causes of hypothyroidism, but by far the most common cause is a condition called Hashimoto’s Disease. Hashimoto’s disease is an autoimmune condition where the thyroid gland is mistakenly attacked by the body’s own immune defenses.
Hypothyroidism can be classified into ‘overt’ hypothyroidism or ‘subclinical’ hypothyroidism.
Overt or ‘full-blown’ hypothyroidism means that you have clinical signs and symptoms of the disease and a positive blood test.
Subclinical hypothyroidism is also called early-stage or mild hypothyroidism. There is a lot of debate in the medical community as to whether or not subclinical hypothyroidism should be treated. But in the case of subfertility or repeat miscarriage, many experts now recommend treatment.
Hypothyroidism and reproductive health
Both overt and subclinical hypothyroidism can affect fertility and reproductive health.
Hypothyroidism is associated with disrupted menstrual cycles, subfertility (difficulty getting pregnant), miscarriage, pregnancy complications and an increased risk to the health and development of the baby. Research also suggests that it might be associated with poorer outcomes during fertility treatment.
What are the symptoms of hypothyroidism?
If you have an underactive thyroid gland, you might experience one or more of the following symptoms:
- Difficulty conceiving
- Weight gain/difficulty losing weight
- Cold intolerance
- Dry skin and brittle fingernails
- Difficulty thinking clearly and concentrationg
On your fertility chart:
Your fertility charts can also reveal signs and symptoms of hypothyroidism. In the Fast Track to Pregnancy Program™, you’ll learn the tell-tale signs to look out for, which can indicate a thyroid problem.
Hyperthyroidism occurs when the thyroid gland makes too much thyroid hormone (T4 and T3).
There are a number of different causes of hyperthyroidism, but the most common cause is a condition called Grave’s disease. Grave’s disease is an autoimmune condition where the immune system makes antibodies that stimulate the thyroid gland into making more thyroid hormone than your body needs.
Hyperthyroidism and reproductive health
Hyperthyroidism is less common than hypothyroidism, but it can also affect your fertility and reproductive health.
Hyperthyroidism is associated with disrupted menstrual cycles and subfertility (difficulty getting pregnant) and may also be associated with miscarriage. In the case of Grave’s disease it’s also associated with pregnancy complications and an increased risk to the health and development of the baby.
What are the symptoms of Hyperthyroidism?
If you have an overactive thyroid gland, you might experience one or more of the following symptoms:
- Difficulty conceiving
- Frequent bowel movements
- Weight loss
- Difficulty sleeping
- Nervousness or anxiety
- Heat intolerance
- Heart palpitations
- Hand tremors
On your fertility chart:
As with hypothyroidism, your fertility charts can also show signs of hyperthyroidism. In the Fast Track to Pregnancy Program™ you’ll learn the tell-tale signs to look out for, which can indicate a thyroid problem.
Another aspect of thyroid dysfunction that’s gaining a lot attention with regards to fertility and reproductive health is the presence of thyroid autoantibodies.
Thyroid autoantibodies are antibodies made by your immune system, which mistakenly attack and damage your thyroid gland. When antibodies attack the thyroid gland, this is known as autoimmune thyroid disease (AITD).
Autoimmune thyroid disease is the most common cause of hypothyroidism (Hashimoto’s disease) and hyperthyroidism (Grave’s disease).
IMPORTANT: Even if you don’t have these conditions and your thyroid gland is functioning normally, it’s still possible to have thyroid autoantibodies.
Thyroid autoantibodies and reproductive health
Thyroid autoantibodies can negatively affect your fertility and reproductive health. In fact around 50% of women with Hashimoto’s or Grave’s disease experience infertility.
Even if you have normal thyroid function (normal TSH – see below), the presence of thyroid autoantibodies still puts you at higher risk of fertility problems, miscarriage and preterm birth. It can also result in poorer outcomes during fertility treatment and may increase the risk of abnormal cognitive development in the baby.
What are the symptoms of thyroid autoantibodies?
Unless you have an overt autoimmune thyroid condition such as Hashimoto’s Disease or Grave’s Disease, there are often no signs or symptoms that indicate the presence of thyroid autoantibodies.
Getting a diagnosis
If you’re experiencing subfertility or miscarriages, and any of the other symptoms mentioned above, it’s imperative that you ask your doctor to test your thyroid function.
To make a diagnosis, your doctor will take into account both your symptoms and the results of a blood test (see below). Your doctor may also perform an examination of your neck, to check the size of your thyroid gland.
In the past, doctors usually treated thyroid disease only if it was overt – that is, only if there were obvious signs and symptoms, and blood test results clearly fell above or below the normal range.
However more and more research is revealing that subclinical hypothyroidism and the presence of thyroid autoantibodies are also associated with difficulty conceiving and negative reproductive outcomes.
As a result, many experts are now treating their trying-to-conceive patients with these more subtle thyroid conditions.
Your blood test result – what you need to know!
The TSH blood test
The standard test that your doctor is likely to give you to assess your thyroid function is a blood test for thyroid stimulating hormone (TSH).
Unfortunately, this test alone doesn’t give you the full story and it won’t tell you if you have thyroid autoantibodies.
There’s also been a lot of debate in the medical community as to what TSH values should be considered ‘normal’ and what TSH values warrant treatment.
By understanding your TSH blood result, you’ll be in a better position to discuss possible treatment with your doctor if necessary.
What is TSH and why is it tested?
Thyroid stimulating hormone (TSH) is a hormone that’s secreted by the pituitary gland at the base of your brain. TSH stimulates your thyroid gland to make thyroid hormone (T4 and T3).
Your body regulates TSH secretion using something called ‘negative feedback’. It’s important to gain a basic understanding of this process, so that you can understand your blood test results.
The secretion of TSH by your pituitary gland works a little bit like a thermostat on your home heating system. A thermostat senses the amount of heat in the air and turns the heating up or down, to keep the air temperature stable. In much the same way, your pituitary gland senses how much thyroid hormone is in your system. It then regulates the amount of TSH it produces accordingly.
If your pituitary gland senses high levels of T4 (high heat), it ‘turns down’ the secretion of TSH. This signals the thyroid gland to make less T4 and T3.
If your pituitary gland senses low levels of T4 (not enough heat), it ‘turns up’ the secretion of TSH. This stimulates the thyroid gland into making more thyroid hormone.
Your pituitary gland in turn, is controlled by an area of the brain called the hypothalamus. The hypothalamus secretes thyrotropin releasing hormone (TRH), which also stimulates the pituitary gland to release TSH.
Like the pituitary gland, the hypothalamus also senses the level of thyroid hormone in your blood. In response it either ‘turns up’ or ‘turns down’ the level of TRH it secretes, causing the pituitary gland to make more or less TSH.
So what does all this mean? Basically, the level of TSH in your blood reflects your level of thyroid hormone:
If you don’t have enough T4 and T3, your TSH will be high.
If you have too much T4 and T3, your TSH will be low.
When your thyroid is making the right amount of thyroid hormone, your TSH should fall within a ‘normal’ range.
What is normal?
Here’s where things start getting a bit murky. There are different opinions as to what TSH range is considered normal, especially when it comes to women who are having difficulty conceiving.
Generally, your TSH is considered ‘normal’, when it falls between 0.45 and 4.5 mIU/L (or thereabouts, depending on the laboratory).
A TSH value of less than 0.45 mIU/L suggests hyperthyroidism.
A TSH value of greater than 4.5 mIU/L suggests hypothyroidism.
A TSH value of greater than 4.5 mIU/L in the presence of normal levels of T4 and T3 indicates subclinical hypothyroidism.
What you need to know if you’re trying to get pregnant!
There has been a lot of debate when it comes to the TSH upper limit of 4.5 mIU/L. Many experts now believe that if you’re experiencing subfertility or miscarriage, an upper limit of 4.5mIU/L is too high and that your TSH levels should be kept below 2.5 mIU/L.
Unless you have overt hypothyroidism or hyperthyroidism, getting treatment from your doctor can be a challenge. But it’s definitely a challenge worth pursuing if you want to optimise your chances of getting pregnant and having a healthy pregnancy.
Studies have shown that treatment for more subtle thyroid issues (subclinical hypothyroidism and thyroid autoantibodies) can reduce the chance of miscarriage, reduce risks to the pregnancy and baby and improve outcomes during fertility treatment.
In the Fast Track to Pregnancy Program™, you’ll learn what tests to ask your doctor for (TSH alone is NOT enough!) and what information to take to your doctor’s appointment, to help push your case. Alternatively, I can help you with this during a personalised online fertility consultation.
How can your thyroid issue be treated?
The good news is that both hyperthyroidism and hypothyroidism can be treated. If you suspect you have a thyroid problem, it’s essential that you consult your doctor for a diagnosis and a treatment plan that’s right for you.
Hyperthyroidism is usually treated with anti-thyroid medications, radioactive iodine or surgery. The right treatment for you will depend on the cause of your hyperthyroidism and your individual circumstances.
Hypothyroidism is usually treated with L-thyroxine. L-thyroxine is a synthetic form of thyroid hormone (T4) and is taken as a once-a-day pill. Some patients and doctors prefer to use desiccated thyroid extract, which is a natural form of thyroid hormone replacement.
Unfortunately, most dietary supplements aimed at supporting the thyroid don’t have scientific evidence behind them, proving that they work.
However, there are some natural options that can help. This includes eating a healthy, whole food diet and ensuring you’re getting the recommended daily intake of iodine and selenium (please be aware that too much iodine can actually make a thyroid problem worse, so I don’t recommend supplementing with iodine unless you need it).
Thyroid treatment during pregnancy
Thyroid hormones play a very important role during pregnancy. They’re essential for a healthy pregnancy and for normal development of the embryo, especially neurodevelopment (brain development).
Pregnancy has a dramatic effect on thyroid hormone production, especially during the first trimester.
During these first 3 months of pregnancy, the growing fetus depends on maternal thyroid hormone for its growth and development. It contributes its own thyroid hormone later on in pregnancy.
It’s extremely important that you maintain healthy levels of T4 and T3 during pregnancy because too much or too little thyroid hormone can increase the risk of complications to the pregnancy and the baby.
This includes preterm delivery, pre-eclampsia, growth restriction and neurodevelopmental delay in the baby, and still birth.
If you have Grave’s Disease (the most common cause of hyperthyroidism) it’s important that you consult your doctor before getting pregnant, to ensure that your thyroid hormone levels are in the healthy range. If they aren’t, you may need treatment before you get pregnant.
If you have, or suspect you might have, an underactive thyroid gland it’s also important to consult your doctor. The changes that occur during pregnancy create a greater demand for T4 and T3. A normal functioning thyroid gland is usually able to meet this increased demand, but if you have overt or subclinical hypothyroidism, your thyroid gland may not be able to cope. Women with thyroid autoantibodies also have an increased risk of developing hypothyroidism in pregnancy.
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