What is hypothyroidism?

The thyroid gland produces two hormones: thyroxine (sometimes called T4) and triiodothyronine (T3). Among other things, thyroid hormones regulate metabolism, the functioning of the nervous, cardiovascular and digestive systems, as well as thermogenesis. The most common thyroid disorder is hypothyroidism. The condition occurs when the gland does not produce enough thyroxine (and thus triiodothyronine, as T4 is converted into T3). It is usually diagnosed after an abnormally high thyroid stimulating hormone (TSH) test result. A woman of childbearing age should have a TSH level of less than 2.5. On the other hand, when trying to have a baby, it would be good for this level to be kept at the lower end of the reference range (less than 2 mU/l and optimally around 1 mU/l) .

Hypothyroidism and pregnancy planning

Thyroid hormones interact with oestrogen and progesterone to maintain the normal functioning of the reproductive system. Women with thyroid dysfunction often experience menstrual disorders and decreased libido . Hypothyroidism can negatively affect important processes related to fertility, particularly the production and release of two key reproductive hormones: folliculotropic hormone (FSH) and lutropin (LH).

In women, FSH stimulates the ovarian follicles to grow in preparation for the release of an egg, while LH helps regulate the menstrual cycle and ovulation. Imbalances of these hormones affect ovulation and are one of the main causes of fertility problems in women .

If you have untreated hypothyroidism, you are likely to find it more difficult to get pregnant. You may have longer or heavier periods, which can cause anaemia, or sometimes your periods may stop altogether. Another problem may be the disappearance of ovulation. Typical symptoms of hypothyroidism furthermore include:

● fatigue,

● muscle soreness,

● problems concentrating, unreasonable fatigue,

● dry skin and hair,

● unexplained weight gain,

● cold intolerance, cold hands and feet .

Doctors recommend that all women planning a pregnancy have their thyroid hormone levels checked before conceiving. If there are problems, implementing treatment can restore fertility and ensure the safety of the pregnant woman and the developing baby.

Hypothyroidism and pregnancy

Hypothyroidism can also interfere with the development of the embryo. This increases the risk of miscarriage. In addition, if a patient is pregnant and hypothyroidism is not treated, the baby may be born prematurely, weigh less than normal, have respiratory problems and reduced mental performance .

If the condition is recognised and treated, there are usually no major complications during pregnancy. The mainstay of treatment for hypothyroidism is levothyroxine. It is likely that you will need higher doses of levothyroxine during pregnancy, especially during the first 20 weeks, to ensure a sufficient supply of thyroid hormones for the baby .

Hashimoto's and getting pregnant

One of the possible and most common causes of hypothyroidism in women is Hashimoto's disease, sometimes called Hashimoto's thyroiditis. This autoimmune disease occurs when the immune system creates antibodies (immune proteins) that attack the thyroid gland. This in turn causes the gland to produce too few hormones.

If you have hypothyroidism and too little thyroid hormones in your blood, for example due to Hashimoto's disease, your body is unable to function normally. Symptoms often include fatigue, weight gain, slow heart rate, dry skin, puffy face, depression, mood swings, digestive problems and heavy periods or irregular cycles causing infertility.

Hashimoto's disease can make it difficult to get pregnant. This is because reduced levels of thyroid hormones interfere with ovulation. If a woman does not ovulate, conception will not be able to occur.

How does Hashimoto's affect pregnancy?

If left untreated, the disease can cause problems for both the pregnant woman and the developing foetus. Women with Hashimoto's disease should consult their doctor before becoming pregnant. Potential complications may include pre-eclampsia, anaemia, miscarriage, placental detachment or postpartum bleeding .

During the first trimester of pregnancy, the foetus is dependent on the mother's thyroid hormone levels, as its brain and nervous system need thyroid hormone for normal development. The effects of maternal hypothyroidism on the foetus can include premature birth, low birth weight or birth defects.

The aim of Hashimoto's treatment is to normalise the mother's thyroid hormone levels. Replacing thyroid hormones with synthetic thyroxine, such as levothyroxine, is both safe and necessary for the health of the mother and the developing foetus. It is also recommended to check thyroid function frequently during pregnancy (every 4-6 weeks) so that the dose of the medication can be adjusted. Thyroid medication is best taken on an empty stomach (30-45 minutes before breakfast) and should be avoided at the same time as prenatal vitamins. The minerals in these vitamins can stop the absorption of thyroid hormone . In addition, iodine (150-200ug/d) should be supplemented before pregnancy and during pregnancy and lactation, as should vitamin D3 and folic acid .