Pregnancy is a unique phase in a woman’s life, marked by significant hormonal changes that can also impact the thyroid gland. Thyroid disorders during pregnancy are relatively common and can have implications for the expectant mother and the developing baby.

What Are The Common Thyroid Disorders in Pregnancy?

Pregnancy can impact thyroid function, and several thyroid disorders can affect pregnant individuals. Some of the common thyroid disorders during pregnancy include:


Hypothyroidism is characterised by an underactive thyroid gland that doesn’t produce enough thyroid hormones. During pregnancy, untreated hypothyroidism can lead to complications for the mother and the developing baby. Pregnant individuals with hypothyroidism must receive proper treatment to maintain thyroid hormone levels within the recommended range.


Hyperthyroidism is the opposite of hypothyroidism, where the thyroid gland produces excessive thyroid hormones. Graves’ disease, an autoimmune disorder, is a common cause of hyperthyroidism. If not managed properly during pregnancy, hyperthyroidism can increase the risk of complications, such as preterm birth and preeclampsia.

Postpartum Thyroiditis

Postpartum thyroiditis is when the thyroid becomes inflamed and disrupted in the months following childbirth. It can lead to temporary hyperthyroidism followed by hypothyroidism. Women with a history of thyroid disorders are at a higher risk.

Subclinical Thyroid Dysfunction

Subclinical thyroid dysfunction refers to mild thyroid hormone imbalances that may not cause noticeable symptoms but can still impact pregnancy outcomes.
Not all thyroid disorders during pregnancy have a clear-cut cause. Pregnancy-related hormonal changes and immune system alterations can contribute to developing or exacerbating thyroid disorders in susceptible individuals. Proper monitoring, diagnosis, and management are essential to ensure the health of both the pregnant individual and the developing baby.

What Are Some Common Symptoms of Thyroid Disorders in Pregnancy?

Thyroid disorders can affect pregnant individuals differently, and the symptoms can vary depending on whether the disorder is causing hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). Here are some common symptoms of thyroid disorders in pregnancy:

Symptoms of Hypothyroidism (Underactive Thyroid)

  • Fatigue and weakness
  • Weight gain
  • Cold sensitivity
  • Constipation
  • Dry skin
  • Hair thinning or loss
  • Muscle aches and stiffness
  • Depressed mood
  • Slowed heart rate
  • Impaired memory and concentration
  • Puffiness or swelling of the face, hands, and feet
  • Irregular menstrual cycles

Symptoms of Hyperthyroidism (Overactive Thyroid)

  • Rapid or irregular heartbeat
  • Anxiety and nervousness
  • Tremors or shaking hands
  • Excessive sweating
  • Heat intolerance
  • Weight loss despite increased appetite
  • Fatigue and weakness
  • Difficulty sleeping
  • Increased bowel movements or diarrhoea
  • Elevated blood pressure
  • Bulging eyes (in cases of Graves’ disease, autoimmune hyperthyroidism
Some symptoms of thyroid disorders can overlap with normal pregnancy-related changes or symptoms. For instance, fatigue, heat intolerance, and mood swings are common in pregnancy. Additionally, some individuals with thyroid disorders might not experience noticeable symptoms.

How Are Thyroid Disorders in Pregnancy Diagnosed?

Thyroid disorders during pregnancy are typically diagnosed through medical history assessment, physical examination, and laboratory tests.

Medical History

The doctor will begin by taking a detailed medical history, including any symptoms you’re experiencing, any family history of thyroid disorders, and any previous thyroid issues.

Physical Examination

A physical examination may be performed to check for signs of thyroid dysfunction, such as thyroid gland enlargement (goitre) or other physical symptoms.

Thyroid Function Tests

Blood tests that measure thyroid hormone levels and thyroid-stimulating hormone (TSH) are essential for diagnosing thyroid disorders. These tests help determine if the thyroid is functioning within normal ranges.
Thyroid function tests include Free T4 (FT4), Free T3 (FT3), and TSH.

Thyroid Antibody Tests

In cases of suspected autoimmune thyroid disorders like Hashimoto’s thyroiditis or Graves’ disease, antibody tests such as thyroid peroxidase antibodies (TPOAb) and thyrotropin receptor antibodies (TRAb) may be performed.

Ultrasound Imaging

An ultrasound of the thyroid gland may be conducted to assess the size, structure, and appearance of the thyroid gland and any nodules present.

Consultation with an Endocrinologist

A referral to an endocrinologist, a specialist in hormone-related disorders, might be recommended for further evaluation and management.

What Are the Health Complications of Untreated Thyroid Disorders in Pregnancy?

Untreated thyroid disorders during pregnancy can lead to various health complications for both the pregnant individual and the developing baby. Proper management of thyroid disorders is crucial to minimise the risks and ensure a healthy pregnancy outcome. Here are some potential health complications of untreated thyroid disorders in pregnancy:

Untreated Hypothyroidism

Risk to the Baby – Untreated hypothyroidism during pregnancy can lead to cognitive and developmental issues in the baby, including lower IQ, learning difficulties, and developmental delays.
Preterm Birth – Hypothyroidism increases the risk of preterm birth, leading to various health challenges for the baby.
Preeclampsia – Untreated hypothyroidism can increase the risk of developing preeclampsia, a serious condition of high blood pressure and organ damage. Anaemia Hypothyroidism can contribute to anaemia, affecting both the pregnant individual and the baby.

Untreated Hyperthyroidism

Preterm Birth – Hyperthyroidism increases the risk of preterm birth and low birth weight. Preeclampsia Similar to hypothyroidism, untreated hyperthyroidism can also increase the risk of preeclampsia.
Thyroid Storm – In severe cases of untreated hyperthyroidism, a condition called thyroid storm can occur, a life-threatening medical emergency characterised by extremely high levels of thyroid hormones.
Foetal Thyroid Dysfunction – Uncontrolled hyperthyroidism can impact the baby’s thyroid function and lead to neonatal hyperthyroidism.
Thyroid disorders can impact the health of the pregnant individual and the developing baby, so addressing any concerns with a doctor is important. If you are pregnant and suspect you have a thyroid disorder or are experiencing symptoms related to thyroid dysfunction, consult your doctor for proper evaluation, diagnosis, and management. Regular thyroid function testing and appropriate treatment can help ensure a healthy pregnancy outcome.

Dr. Cho Li Wei 朱丽薇医生

Consultant Endocrinologist
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