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  • Writer's pictureGrace Health

Can An Under Or Over Active Thyroid Affect My Menstrual Cycle?

Many women don’t think about their thyroid until there’s something wrong with it. Some may not even know what it is, but Grace is here to help.

Having issues with your thyroid can lead to changes in your menstrual cycle. While you might not currently have problems with your thyroid, looking out for changes in your period could help you catch the problem early on. Here’s what you need to look for when detecting an overactive or underactive thyroid.

What’s a thyroid anyway?

Your thyroid is a small butterfly-shaped gland found at the base of your neck, just below your Adam's apple. This gland makes thyroid hormone that travels in your blood to all parts of your body. The thyroid hormone is very important. It controls your body's metabolism in many ways, including how fast you burn calories and how fast your heart beats.

How is the thyroid related to the menstrual cycle?

Aside from the metabolism and heartbeat rate, the thyroid also plays an essential role in your reproductive health. It directly affects your ovaries and indirectly interacts with sex hormone-binding globulin (SHBG). SHBG is a protein that "sticks" to reproductive hormones so they can be carried throughout your body. Menstrual problems tend to be most common in those with severe thyroid disease and less common in those with mild or moderate cases.

Hypothyroidism vs. Hyperthyroidism what’s the difference?

Menstrual cycle irregularities can be due to an under-active or over-active thyroid. How symptoms present could depend on the type of thyroid disorder.


Is the under-active thyroid gland and occurs when the body produces too little thyroid hormone. It, in turn, slows your metabolism, which can lead to weight gain. Some of the menstrual problems associated with hypothyroidism include:

  • Irregular cycles - Hypothyroidism could cause one to miss periods or have them less often.

  • Frequent menstrual bleeding - People with hypothyroidism may also have menstrual periods that last longer or occur more often than people without the condition.

  • Heavy menstrual bleeding - This is a common symptom in many people with hypothyroidism.

  • Absent menstrual cycles - Some people with hypothyroidism may not menstruate.

  • Infertility and miscarriage - People with untreated hypothyroidism may have trouble conceiving and are more likely to experience miscarriage and pregnancy complications.


This is the over-active thyroid gland. This means the body produces too much thyroid hormone. Menstrual irregularities seen with hyperthyroidism include:

  • Absent or infrequent periods - This is the most common symptom seen with severe hyperthyroidism.

  • Light and short periods - Bleeding may be less than usual.

  • Decreased fertility - Not ovulating can impact your fertility.

  • Risk of miscarriage - In addition, excessive thyroid hormone production during pregnancy increases the risk of miscarriage.

How are thyroid diseases diagnosed?

Since thyroid symptoms are the same as many other health problems, it can be hard to tell if you have a thyroid disease. Your doctor may start by asking about your health history and if any of your family members have had thyroid disease. Your doctor may also give you a physical exam and check your neck for thyroid nodules.

Depending on your symptoms, your doctor may also do other tests, such as blood tests and a Radioactive iodine uptake test. High levels of radioiodine mean that your thyroid makes too much of the thyroid hormone. Low levels mean that your thyroid does not make enough thyroid hormone.

Can thyroid disease affect my chances of conceiving?

Yes! Both hyperthyroidism and hypothyroidism can make it harder for you to get pregnant. This is because problems with the thyroid hormone can upset the balance of the hormones that cause ovulation. Hypothyroidism is also known to cause your body to make more prolactin, the hormone that tells your body to make breast milk and too much prolactin can prevent ovulation.

What about pregnancy?

Thyroid hormones are necessary for the baby's brain development while in the womb. It can be harder to diagnose thyroid problems during pregnancy because of the change in hormone levels that normally happen during pregnancy. But it is especially important to check for problems before getting pregnant and during pregnancy. Uncontrolled hyperthyroidism and hypothyroidism can cause problems for both mother and baby.

Hyperthyroidism that is not treated during pregnancy can cause:

  • Premature birth (birth of the baby before 39 to 40 weeks, or full-term)

  • Low birth weight (smaller than 5 pounds)

  • Preeclampsia is a serious condition starting after 20 weeks of pregnancy. Preeclampsia causes high blood pressure and problems with the kidneys and other organs. The only cure for preeclampsia is childbirth.

  • Thyroid storm (sudden, severe worsening of symptoms)

  • Fast heart rate in the newborn, which can lead to heart failure, poor weight gain, or an enlarged thyroid that can make it hard to breathe

  • Miscarriage

Hypothyroidism that is not treated during pregnancy can cause:

  • Problems with the baby's growth and brain development

  • Preeclampsia

  • Low birth weight (smaller than 5 pounds)

  • Anaemia (lower than normal number of healthy red blood cells)

  • Miscarriage

  • Stillbirth


Both Hypothyroidism and Hyperthyroidismcan have an impact on your menstrual cycles. Symptoms may range from heavy and frequent periods to irregular and absent cycles. These symptoms are due to how thyroid hormones impact reproductive hormone production. Menstrual irregularities could also affect fertility and pregnancy.

If you have menstrual irregularities and are concerned about a thyroid problem, please see your doctor.

Stay informed, stay in control What stood out for you about your thyroid? Share in the comments

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