Thyroid levels in pregnancy
During pregnancy, the need for thyroid hormones increases. Pregnancy hormones stimulate the thyroid to increase its production. In the first three months of pregnancy in particular, there is naturally an increase in thyroid hormones in the blood. At the same time, the level of the regulatory hormone TSH drops. Due to the adaptation processes, which also include a change in thyroid function during pregnancy, specific limit values for thyroid hormones apply depending on the stage of pregnancy. If these are exceeded or not reached, this can have a negative effect on the child's development without treatment. If it is suspected that there is a disorder of the thyroid function during pregnancy, the thyroid values in the blood should be examined in order to initiate treatment in good time if necessary.
Classification of values
The thyroid values during pregnancy often cause confusion, as there are many possible constellations with increased and decreased values depending on the cause. In addition, depending on the stage of pregnancy, different limit values apply, i.e. the range in which the values can be classified as normal. Therefore, the most important and most common constellations are compiled here.
In the first three months of pregnancy, TSH, the thyroid regulating hormone, should be between 0.1 and 2.5. At higher values, there may be a hidden hyperthyroidism, which is often otherwise not noticeable. Only if the thyroid hormones T3 and T4 are also decreased is there a hypothyroidism that leads to symptoms. Treatment with thyroid hormone tablets should, however, already be started if only the TSH is elevated.
In the case of an overactive thyroid, the laboratory values are usually changed in exactly the opposite way. A TSH that is too low, i.e. below 0.1 in the first three months or below 0.2 in the second trimester of pregnancy or below 0.3 in the last phase, indicates overfunction, which often does not cause any symptoms. Only when T3 and T4 are increased at the same time do complaints usually arise. Here, too, suspicious TSH should, if necessary, be treated with tablets that reduce thyroid hormone production.
How do the values change during pregnancy?
During pregnancy, the mother's thyroid has to take care of the child. The thyroid hormones are very important for the healthy physical and mental development of the growing baby. Therefore, natural remodeling processes in the woman's body lead to a change in thyroid function, which can also be made visible by determining the values in the blood.
Especially in the first trimester of pregnancy, pregnancy hormones cause the thyroid to produce more hormones. As a result, the regulatory hormone TSH drops, so that lower values of up to 0.1 mU / L can be regarded as normal in this phase.
In the further course this effect decreases again and the TSH should rise again. If this is not the case, this could indicate an overactive thyroid disease such as Graves' disease.
Read more about this under Graves disease
The thyroid hormones, especially the T4 (Thyroxine) is usually increased in the first months of pregnancy and decreases again in the course of the pregnancy. If the thyroid values are outside the normal range appropriate for the respective phase of pregnancy, a more precise diagnosis (e.g. by means of further blood tests) should be carried out and, if necessary, therapy should be started promptly.
What should the thyroid values be when you want to get pregnant?
If there is a desire to conceive, the mother's optimal thyroid values are very important. In return, a thyroid dysfunction is a common cause of a failure to have children, which often goes unnoticed. Therefore, if the desire to have children is not fulfilled, the thyroid values should also be determined before further measures.
The most important marker is the TSH. In the best case, it should be around 1mU / L. Even if values up to 2.5 are harmless for the mother, women with lower values have a higher chance of becoming pregnant. However, values that are too low, which are less than 0.5mU / L, can also be responsible for preventing pregnancy. The other thyroid values usually do not have to be determined for a TSH in the normal range. They are only used for a more precise assessment in the event of deviations. An overactive with increased and an underactive with decreased values for the thyroid values T3 and T4 should be treated before the onset of pregnancy.
Read more about this under Thyroid levels
What do I do if my thyroid levels are too high during pregnancy?
The first question is which thyroid levels are too high.
If the control hormone TSH is increased, there is usually an underfunction and if the thyroid hormones (T3 and T4 or thyroxine) are increased, there is overfunction. Depending on the functional status, there are different options for treatment if the doctor considers it necessary.
In the case of hypofunction, i.e. if the TSH is too high, treatment with thyroid hormones takes place, which is taken daily as tablets. This can prevent the child's developmental disorders. In contrast, an increase in thyroid hormones (T3 and T4) occurs naturally in many pregnant women in the first few months. There is an increased need and the thyroid gland is therefore stimulated to produce more hormones. In most cases no treatment is necessary and the values usually return to normal during pregnancy.
Occasionally, Graves' disease also occurs during pregnancy. In addition to an increase in thyroid hormones and symptoms of hyperfunction such as tremors, restlessness and increased sweating, the eyes can protrude. If Graves' disease is detected by special blood tests, treatment must also be given immediately during pregnancy. In addition, special drugs are used that inhibit the thyroid function. This is usually either propylthiouracil or thiamazole. The dosage is chosen as low as possible in order to reduce negative effects on the child. These cannot be ruled out, but the benefits of a treatment outweigh this.
Read more about this under Therapy for an overactive thyroid
What do I do if my thyroid levels are too low during pregnancy?
If the thyroid values are too low during pregnancy, two fundamentally different disorders are possible, depending on which values are lowered. A too low TSH indicates an overfunction. However, it is essential to note that especially in the first three months of pregnancy there is naturally an increased hormone production and thus a decrease in TSH. Therefore, depending on the phase of pregnancy, very low values up to 0.1 and 0.3 can be normal, although under other circumstances this would indicate a noticeable hyperfunction.
Nevertheless, the values should be checked further during the course of pregnancy. If the TSH is still lower, however, further diagnostics should be carried out. Additional, special thyroid values (antibodies) are also determined, as one possible cause is Graves' disease. As a rule, if the TSH values are too low due to an overactive thyroid, tablets are prescribed that reduce the thyroid's hormone production. Even if these can potentially have a negative effect on the baby, they should be taken, as a lack of treatment would be much more dangerous for the child's development. The doctor will also choose a dosage that is as low as necessary.
If, on the other hand, the thyroid hormones T3 and T4 are too low in the case of abnormal thyroid values, there is hypothyroidism, which requires different diagnostics and therapy. Often a special thyroid disease called Hashimoto is also present here. This can also be detected or excluded by determining antibodies typical for the disease.
Read about this too Hashimoto's thyroiditis
Hypofunction during pregnancy should definitely be treated with thyroid hormones in the form of tablets. Otherwise there is a risk of serious consequences for the child, such as mental or physical development disorders. The risk of a miscarriage is also increased with untreated hypothyroidism.
Read more about this at: Hypothyroidism in pregnancy
What influence do pregnancy values have on the development of my baby?
The thyroid hormones play a central role in controlling the baby's physical and mental development. Since it is initially unable to produce the hormones itself, it is dependent on the production of the maternal thyroid. The hormones reach the child via the blood and placenta.
An underactive thyroid can therefore have fatal effects on the development of the child and must be recognized and treated, otherwise it can even result in a miscarriage. However, an overactive thyroid gland in the mother can also be very harmful to the growing baby. It is therefore of great importance that the thyroid values are as close as possible to the normal range of the respective stage of pregnancy. If there is a suspicion that the mother has a thyroid dysfunction, the thyroid values in her blood should be determined.