HYPOTHYROIDISM DURING PREGNANCY

What is the thyroid gland?

The thyroid gland is located in the neck alongside your Adams apple. It releases thyroid hormones into the blood which power the cells of the body. The thyroid gland is controlled by another gland found in the brain known as the pituitary gland.

Underactivity of the thyroid gland is also called hypothyroidism or myxoedema. Underactivity of the thyroid gland occurs in approximately 1 in every thousand pregnancies.

When the gland becomes underactive the thyroid gland produces less thyroid hormone which results in a general slowing down both physically and mentally. When the thyroid gland is underactive you may experience a number of symptoms. Some of the more common symptoms are listed below

Loss of energy
General tiredness
Dislike of cold
Tremor
Weight gain and bloating
Slow pulse
Constipation
Muscle weakness
Dry skin and hair
Hoarse voice

Each patient is different and you may experience only a few of these symptoms

If the underactivity is not corrected then there is a risk of miscarriage and your baby may be smaller than expected.

Underactivity of the thyroid gland may be caused by an "autoimmune condition" This means that cells which normally protect the body from infection develop a "fault" and begin to recognise the thyroid gland as foreign material and attack it. This damages the thyroid gland and it is less able to produce thyroid hormones. It is not yet known why cells develop the fault that causes them to attack the thyroid gland. Underactivity of the thyroid gland may also occur in people who have previously had thyroid surgery or radioactive iodine treatment for overactivity of the thyroid gland in the past.

A blood test is taken to measure the level of thyroid hormones in the blood especially TSH. This will be repeated regularly during your pregnancy to monitor therapy.

Underactivity of the thyroid gland is treated with an artificial thyroid hormone called thyroxine. Thyroxine is very similar to natural thyroid hormones and as long as it is given in the correct dose it has virtually no side effects. You will be seen more frequently at the ante-natal clinic for regular blood tests to ensure that you are receiving the correct dose of thyroxine. The demand for thyroxine increases in the latter half of pregnancy and may require a slight increase of your thyroid therapy. The specialist checks for this by measuring your blood TSH level at regular intervals during your pregnancy.

As long as thyroxine is given in the correct dose it will have no effect on you baby as very little passes across the placenta to your unborn baby.

It is safe to breast feed whilst taking thyroxine.

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Ó NHS Tayside; 2006; version 1.0

Disclaimer; no liability whatsoever is accepted for information given and all such information, especially with regard to drug usage (UK version provided), must be checked with a person’s health provider.