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HealthInfo West Coast-Te Tai Poutini

Thyroid disease in pregnancy

Matenga repe tenga i te hapūtanga

If you have an overactive thyroid (hyperthyroidism) or underactive thyroid (hypothyroidism), you will need some extra care and monitoring while you are pregnant. This is important to keep you and your pēpi (baby) well.

Overactive thyroid

You have a normal chance of becoming pregnant as long as your overactive thyroid is controlled.

It is best not to become pregnant while you are being treated for an overactive thyroid. The medicines can harm a baby's thyroid gland.

But if you get pregnant, it is important to keep taking your medicine. Your general practice team will arrange for you to see a specialist. They will work out what dose of medicine will control your overactive thyroid while reducing the risk to your pēpi.

After you have finished your treatment, you will have a normal chance of becoming pregnant.

You will need to have regular thyroid blood tests while you are pregnant.

Unlike other women, you will not need to take iodine supplements while pregnant because they could make your overactive thyroid worse.

You cannot have a radionuclide thyroid scan or radioiodine treatment while you are pregnant, as they are not safe for your pēpi.

Underactive thyroid

If you have an underactive thyroid (hypothyroidism), you will need regular blood tests when planning a pregnancy and through your pregnancy.

It is important that you have the right dose of thyroxine for both you and your pēpi. If you do not have enough thyroxine, you could have problems. For example, anaemia (not enough red blood cells), heart failure, problems with the placenta or bleeding after delivery.

Most women need to take a higher dose of thyroxine while they are pregnant. Then they go back to their normal dose once their pēpi is born.

Written by HealthInfo clinical advisers. Last reviewed November 2024.

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Thyroid

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