Hypothyroidism and Hyperthyroidism in Pregnant and Breastfeeding Mothers Explained

By the team at Speedoc,
May 05, 2021

The responsibility of being a mother starts the moment you see those two blue lines on the pregnancy test kit. Yes, you're expecting a new addition to your family!

Your responsibility as a mother, however, begins now, not just when your baby is born. It's a tall order especially when you're at risk of a thyroid condition during pregnancy.

The truth is our bodies do not always respond to or cooperate with our wishes and during pregnancy, there could be unexpected situations that could derail our well-charted plans. One of the most notable threats to pregnant women would be thyroid dysfunctionalities - its prevalence makes thyroid conditions potent.

In fact, the National Institute of Diabetes and Digestive Kidney Diseases has reported that in every 100 pregnant women, 3-4 suffer from some form of thyroid disease.

The most common reason for thyroid disorders worldwide is iodine deficiency and it can affect anyone at any age; the most common, however, continues to be with women. Here are some nuggets of info about thyroid conditions worldwide to digest:

  • Approximately 1 billion people stand the risk of iodine deficiency globally.

  • Thyroid disease is the second most common hormone disorder for pregnant women, regardless of where we live.

  • If left untreated, problems with the thyroid could lead to infertility, miscarriage, preeclampsia, and postpartum thyroid disease.

  • The hormone created by the thyroid is absolutely important to your baby's brain and nervous system.

  • If the mother is suffering from untreated thyroid problems, the infant could be born with low birth weight and, potentially serious conditions like congestive heart failure.

  • Hypothyroidism and Hyperthyroidism are 10 times more common in women compared to men.

If you’re not familiar with what our thyroid does and what preventive measures should be taken to ensure that my child will not be affected, read on to find out more about the most commonly asked questions about pregnant mothers with thyroid conditions.

Can Hypo-, Hyperthyroidism Affect My Pregnancy?

The thyroid is a gland that produces thyroid hormones that control how your body utilises energy. It, therefore, affects the way nearly every organ in your body works.

To your little one, the condition of your thyroid is absolutely essential to the development of its brain and nervous system. In fact, during the first trimester, your baby depends on your supply of thyroid hormone, which comes in through the placenta, exclusively. After 12 weeks of development, your baby’s thyroid should have developed to a point where it can start working on its own to a certain extent.

It will not, however, produce enough thyroid hormone until the 18th to 20th week of your pregnancy.

Considering the length of time it takes for your unborn child to properly develop, thyroid disease cannot be taken lightly, as it could have severe implications on both you and your baby.

Apart from the pregnancy spells combined with the effects of a thyroid condition, you could also experience a dangerous rise in blood pressure during late pregnancy, a sudden severe, worsening of symptoms and congestive heart failure.

Similarly, an overactive thyroid in a newborn baby can lead to a fast heart rate, which in time leads to heart failure, early closing of the soft spot in the baby’s skull, irritability, and poor weight gain.

These are good enough reasons for you to ensure that you and your child’s health is in good condition by keeping your thyroid hormone levels within a healthy, manageable range.

What are the Most Common Causes of Hypo- and Hyperthyroidism During Pregnancy?

Hypothyroidism and hyperthyroidism may sound like they are more or less the same but their cause and effect are completely different.


When it comes to hypothyroidism, the most common cause for it would be the autoimmune disorder known as Hashimoto’s thyroiditis.

Hypothyroidism can occur during pregnancy due to the initial presence of a chronically inflamed thyroid gland, or inadequate treatment of a woman already known to have hypothyroidism from a variety of causes.

According to the American Thyroid Association, approximately 2.5% of women will have a thyroid-stimulating hormone level of greater than 6mlU/L (slightly elevated) and 0/4% will have a thyroid-stimulating hormone level of greater than 10mlU/L during pregnancy.


Overall, the most common cause of hyperthyroidism in pregnant women is Grave’s disease, which occurs in 0.2% of pregnant patients.

This is a result of an overproduction of thyroid hormone by the entire thyroid gland. In addition to other usual causes of hyperthyroidism is the characterisation by one or more nodules in the thyroid that may gradually grow and increase activity.

The total output of thyroid hormone into the blood is then greater than normal. This is also known as toxic nodular goiter.

What Are the Symptoms of Hypo-, Hyperthyroidism During Pregnancy?

Hypo- and hyperthyroidism presents itself in different forms.

The symptoms of an underactive thyroid (hypothyroidism) during pregnancy include:

  • Tiredness

  • Oversensitivity to temperature, especially cold

  • Unexplained weight gain

  • Constipation

  • Depression

  • Slow movements and thoughts

  • Muscle aches and weakness

  • Muscle cramps

  • Dry and scaly skin

  • Brittle hair and nails

  • Loss of libido (sex drive)

  • Pain, numbness, and a tingling sensation in the hand and fingers (carpal tunnel syndrome)

  • Irregular periods or heavy periods

Symptoms of an overactive thyroid (hyperthyroidism) during pregnancy include:

  • Irregular heartbeat

  • Heightened nervousness

  • Severe nausea or vomiting

  • Hand tremors

  • Insomnia

  • Weight loss or low weight gain beyond the expectation of a typical pregnancy

If you are pregnant and have any of the symptoms mentioned above, it is advisable to contact your doctor or healthcare provider immediately. It is a good idea to understand the link between your thyroid function and pregnancy right off the bat.

How is Hypo-, Hyperthyroidism Diagnosed?

When you’re expecting, the thyroid gland must work overtime to increase its production of thyroxine. This is because some of the hormone is transferred to the fetus until the baby can produce its own.

That’s why we should be mindful when we start experiencing symptoms of either hypothyroidism or hyperthyroidism.

The best way to diagnose either hypothyroidism or hyperthyroidism is with consultation and health tests by a physician. So, if you have any of the symptoms, consult your physician as soon as possible.

If the physician suspects either hypothyroidism or hyperthyroidism, a simple physical examination will be carried out to detect the tell-tale signs.

The warning signs of hyperthyroidism detected through a physical examination include an enlarged thyroid gland and a rapid pulse. The physician will also look for moist, smooth skin, and a tremor of your fingers. This diagnosis will be confirmed by a laboratory test that measures the amount of thyroid hormones present in your bloodstream. A high level of thyroxine and a low level of thyroid-stimulating hormone indicates an overactive thyroid. Your doctor may also want to obtain a picture of your thyroid through imaging for further analysis.

For hypothyroidism, the doctor will have a close look at your medical history and the symptoms you’re experiencing throughout your pregnancy. After which, a blood test that measures the level of thyroid-stimulating hormone, and sometimes the level of the thyroid hormone thyroxine will be taken. A low level of thyroxine and a high level of thyroid-stimulating hormone indicates an underactive thyroid.

Is It Safe to Breastfeed While I’m Taking Beta-Blockers, Thyroid Hormones, or Antithyroid Medicines?

Certain beta-blockers are safe to take even when you’re breastfeeding your child as only small amounts end up in breast milk. Nonetheless, taking the smallest dose to relieve symptoms is best.

Although only a negligible amount of thyroid medication reaches your baby through breast milk, making it relatively safe to take while breastfeeding, it is best to consult with your doctor and obtain their recommendations.

What Should I Eat During Pregnancy to Help Keep My Thyroid and My Baby’s Thyroid Working Well?

In general, eating a healthy, balanced, nutritious diet during pregnancy is important. Whatever you are feeding your body is linked to helping your baby develop their brain and birth weight.

However, specific to thyroid functionality, research has found that certain foods are closely linked to a healthy thyroid.

For example, the thyroid uses iodine to make thyroid hormones. Thus, iodine is a crucial mineral for you throughout your pregnancy because your baby also gets iodine from your diet. And you WILL need more of it while you’re pregnant.

Some of the best iodine-rich foods to include in your daily diet include dairy foods, eggs, meat, poultry, and iodised salt. Experts also recommend taking iodine tablets with 150mg of iodine to make sure you’re getting sufficient levels of iodine.

Breastfeeding mothers need more iodine because their baby will be getting his or her iodine content from breast milk.

Conversely, do take note that taking too many iodine-rich supplements could bring about the opposite effect, indirectly causing thyroid problems instead. Thus, you should talk to your doctor to discuss the eating plan that is right for you and the supplements that you should take during your pregnancy and while breastfeeding.

What is Postpartum Thyroiditis and Am I at Risk of Developing it?

Postpartum thyroiditis is an inflammation of the thyroid that affects about 1 in every 20 women during their first year after giving birth, as reported by the National Immune and Kidney Disease Association. The inflammation causes stored thyroid hormones to leak out of your thyroid gland. Initially, the leakage raises the hormone levels in your blood, following which the damage to your thyroid may cause it to become under-active.

How do you know you’re suffering from postpartum thyroiditis? Some of the common symptoms include irritability, trouble dealing with heat and sleeping, a fast heartbeat, and tiredness.

As you can see, your journey as a new mother does not end with the birth of your child. It is important to look after your health as a new mother too. If these symptoms persist throughout the first few months after the birth of your baby, call your doctor for a chat as soon as possible.

At Speedoc, we provide services to help you monitor and manage your thyroid conditions, so download our app today to book your thyroid chronic disease management package.

Let Speedoc Help Diagnose and Manage Your Thyroid Condition

In conclusion, while thyroid problems can be hard to diagnose in pregnancy due to the higher levels of thyroid hormones and other symptoms that occur both in pregnancy and thyroid disorders, keeping an eye out for symptoms and diagnosing early allows you to have a healthy pregnancy that is as free from worry as possible. As a continuation of diagnosis, you should have regular thyroid function tests and take the prescribed medication to maintain your thyroid levels.

At Speedoc, we provide services to help you monitor and manage your thyroid conditions with our Chronic Disease Home Management (CDHM)™ programme.

Download our app to enroll in CDHM™ for thyroid disorders today!