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Thyroid Disorders: Your Guide to Fertility and Pregnancy

Updated: Feb 13, 2023

Growing Up we were provided with all the information in Sex-Ed, on how not to become pregnant.

Yet there was no focus on how to become pregnant. Periods, hormonal cycles, words like ovulation are not understood by many of us. Often the reason to explore / understand these female characteristics, is when we are trying to work out, why we aren't falling pregnant.

Infertility can be caused by many different things. And, for 1 in 4 couples a cause cannot be identified (1). Infertility can be from the male or the female or a combination of both. In women it is most commonly caused by problems with ovulation – sometimes with the egg not being released at all or other times with an irregular egg release. Problems with ovulation can be a result of conditions like PCOS, thyroid problems and premature ovarian failure, but honestly, there is a web list of possibilities.

In this blog, I am going to focus on how thyroid conditions can affect your fertility, with both an overactive thyroid gland and an underactive thyroid gland can prevent ovulation occurring. So, let’s take a look….


Having hypothyroidism (low thyroid hormone levels) can affect many different aspects of menstruation and ovulation. It can lead to have high prolactin levels - which can then cause either no egg to be released during ovulation or irregular egg releases and difficulty conceiving (2-6). It can also impact other fertility hormone levels such as estrogen and progesterone which can cause irregular ovulation, increased rates of miscarriage and premature births (3).

Hypothyroidism can also cause a shortened second half of the menstrual cycle – which then might not allow a fertilised egg enough time to attach itself to the womb (3-5). And then on top of all of that, it can also cause other symptoms such as fatigue, weight gain, an intolerance to the cold, low mood, muscle aches, poor memory or attention span and constipation (4).

Many people with hyperthyroidism also experience menstrual disturbances – with people with hyperthyroidism having lighter and more irregular periods (5). Just like hypothyroidism, it can cause the increased production of the hormone prolactin – then causing the disturbance of eggs being released (5). Other symptoms of those with hyperthyroidism include uncontrolled weight loss, hair loss, changes in mental health (anxiety being the most common), food cravings and extreme hunger, heat intolerance and heart palpitations (7).

Ideally, before becoming pregnant you should have your thyroid hormones checked especially if you have a known thyroid disorder, or family history of a thyroid disorder. Tackling the symptoms early on in the pregnancy planning stages allows for earlier treatment which will ultimately allow for a more successful outcome.


The symptoms of hypothyroidism are actually quite similar to that of early pregnancy symptoms including extreme tiredness, weight gain, sensitivity to the cold, muscle cramps and difficulty concentration – so you could easily confuse yourself as to what you’re experiencing (4). Your requirements for your thyroid hormones actually increase during pregnancy in order to support both the baby and you – which means not getting on top of it quickly can sadly impact upon your baby’s growth and brain development.

It is also very important to seek out appropriate treatment with hyperthyroidism especially when you are pregnant as it has been associated with a fast foetal heart rate, small for age babies, prematurity, still births and birth defects (8).

Even though the treatment of thyroid disorders in pregnancy is generally the same as that prior to becoming pregnant, you are going to want to tell your doctor straight away. This just makes sure that you are receiving proper treatment and that any adjustments are made as soon as possible. You might also need close monitoring throughout your pregnancy to make sure that everything is going okay.

Post pregnancy

After giving birth a condition called post-partum thyroiditis affects a small percentage of women – it is when a woman’s thyroid gland becomes inflamed after having a baby (9). It affects between 3 in 100 to 2 in 25 pregnant women – however you are more likely to get this condition if you have a history of thyroid problems (9). It can last between a few weeks to months (9). Some of the symptoms can also be hard to distinguish from the struggles that are often associated with being a new parent. The symptoms may occur in two stages:

  • In the first stage they may look like hyperthyroidism – you may be anxious, cranky, have a rapid heart rate, experience a sudden loss of weight, have trouble with the heat, being fatigued or having difficulty sleeping

  • In the second stage, the symptoms of hypothyroidism return – you may have no energy, trouble with cold temperatures, constipation, dry skin, have aches and pains, and have a foggy brain.

It is really important to say that no two women are a like in how this affects them.

How can I help support my Thyroid?

Well firstly let’s not underestimate the importance of exercising regularly, eating healthily, and reducing your stress levels when it comes to the health of your thyroid. Now, I’m not saying that doing everything I am about to mention is automatically going to fix everything, as everybody is different – but these changes in combination with your current thyroid treatment plan can help try to help get your thyroid in the best place it can be to help you conceive.

Here are a few of my tips:

  • Eat a nutritious diet: Try to include rich sources of iodine, selenium, vitamin D and zinc as these nutrients help to support your thyroid (we will explore this later). A pre-conception food plan needs a minimum of 3 months of implementation.

  • Physical activity: Exercise is thought to boost your fertility – but also incorporating it can help to reduce your thyroid symptoms like low mood and trouble sleeping.

  • Manage stress levels. Easier said than done, I know. But stress communicates to our body things may not be safe. Our body will always protect us, and this can include preventing pregnancy if it perceives it's not safe to bring a child into the world. Invest times into strategies which can be beneficial to you.

  • Recognise what you do and do not have control over: Part of managing stress is understanding what you have control over and what you don’t. You have control over what food you eat and how much you exercise, but sadly you don’t have control when or if your body ovulates, or when or if fertilisation occurs.

  • Seek support if needed: Finding support and opportunities to talk about the experience with other's who understand may be one of the most important valuable things that you can do.

Vitamins and minerals

Ensuring that you are meeting your requirements for certain vitamins and minerals is essential for maintaining and/or improving the health of your thyroid.

  • Iodine is a really important nutrient for your fertility seeing as it plays a pretty essential role in producing thyroid hormones in the body. The good news is that it is found in a wide range of nutritious foods including seafood, fish, bread, iodised salt, seaweed, eggs, fruits, and vegetables (9).

  • Selenium also affects the production of thyroid hormones. It can also promote healthy follicles in the ovaries, which develop and release the eggs, as well as helps to protect against birth defects and miscarriages caused by DNA damage. We can increase our intake by including rich sources such as Brazil nuts, sunflower seeds, chicken, lentils, legumes, eggs, and pork in your diet (10).

  • Vitamin D plays a significant role in female fertility as it is associated with higher odds of conception and is critical in supporting a healthy pregnancy. Regular sun exposure is how we get the majority of our vitamin D. To get enough we want to try to aim to get around 10 to 30 minutes, most days of the week (11).

Zinc supports fertility by regulating normal hormone function, cell division and ovulation. It can be found in foods like red meat, seafood, milk products, poultry, and eggs, as well as plant foods like legumes and wholegrains (12)


If you are doing any research into what you can do with your diet in order to improve the health of your thyroid, you are probably going to come across the word “goitrogen”. Now, this is essentially just a fancy name for compounds that are found in vegetables like broccoli, kale, cauliflower, cabbage, and Brussel sprouts. They can block thyroid hormone production and function, but this usually only occurs if you have an iodine deficiency as well (13).

These kinds of vegetables are extremely nutritious, so we don’t really want to be limiting them – so please don’t let this be the reason why you skip these kinds of foods. The good news is that when consumed in regular portion sizes, around half to a fully cup a day, they shouldn’t cause any concerns. However, if you are concerned, the goitrogenic effect of cruciferous vegetables is erased when they are cooked (13).

The Bottom Line

Exercising regularly, eating healthy, and reducing your stress levels isn’t going to automatically mean that you are going to get pregnant – there is too many competing factors in order to give you a definite answer as to what is going to work.

Doing these things, in combination with your current thyroid treatment plan can help to get your thyroid in the best place that it can be - which can then help you get pregnant and carry the baby to term. If you have a thyroid disorder and you are trying to conceive, and nothing seems like it is working, then please reach out.

I work with clients in coaching programs, which is ideal for anytime trying to conceive. Real changes, in a supported personalised approach.

Nicole Barber Dietetics

8 week coaching programs


This blog was written by Makayla Zok (APD).



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