What Should You Know About Hyperthyroidism In Pregnancy


The thyroid gland is a key organ of the body. In pregnancy, it can change, sometimes in a normal way, and other times pathological. Today we are going to tell you about hyperthyroidism in pregnancy and everything you should know about this condition.

Hyperthyroidism in pregnancy is one of the least common forms of thyroid disease during pregnancy. It is estimated that it is present between 0.05 to 0.2% of women in this state.

It is not easy to diagnose hyperthyroidism in pregnancy, as the physiological changes in the mother’s body could conceal some symptoms. If the diagnosis is confirmed, this will have a very different treatment than that carried out in the non-pregnant woman. We will tell you.

Forms of hyperthyroidism during pregnancy

The thyroid function presents great changes in women during pregnancy. This is necessary for normal growth and development of the fetus to occur. 

Among the main transformations are the following:

  • The abrupt increase in thyroxine production: occurs during the first trimester of pregnancy and can lead to transient hyperthyroidism.
  • Elevation of thyroxine-binding globulin (TBG): TBG is a protein that transports substances related to the thyroid gland. Its concentration increases due to the increased production of estrogens during pregnancy.
  • Modifications in iodine stores: there is a decrease in iodine before the 20th week of gestation, which is expected. This mineral is basic for the production of levothyroxine.

In pregnancy, hyperthyroidism is often transitory when it is due to physiological changes or hyperemesis gravidarum; that is, morning vomiting. However, in most cases, the main cause is Graves’ disease.

This occurs in one in 500 pregnant women and consists of an immune-based pathology that accelerates the functioning of the thyroid gland, stimulating it excessively. If not handled immediately and properly, it can lead to serious complications for both mom and baby.

Hyperthyroidism in pregnancy is difficult to suspect because many symptoms seem normal for pregnancy.

How is hyperthyroidism in pregnancy diagnosed?

Many of the manifestations of hyperthyroidism in pregnancy overlap with the changes produced by pregnancy. This means that the symptoms are masked and become difficult to identify.

Signs such as heat intolerance, palpitations, nervousness, difficulty gaining weight, and resting tachycardia are common features of hyperthyroidism and pregnancy itself.  The same goes for the improvement in the quantity of the thyroid gland.

Therefore, the results of biochemical tests should be carefully examined. In general, when TSH (thyroid-stimulating hormone) levels are below the normal range, and the levels of thyroxine (T4) and free thyroxine (FT4), or triiodothyronine (T3) are elevated, there is hyperthyroidism.

it is increased during the first trimester of pregnancy and postpartum When there is Graves Basedow disease, It is suspected to be present if the patient had symptoms before pregnancy, has a previous diagnosis of hyperthyroidism, or has had a child with thyroid dysfunction.

Risks of the disease

Hyperthyroidism in pregnancy can have very serious consequences for both the mother and the fetus. Until after birth, some effects last. So far, scientific evidence has identified the following complications:

  • Increased risk of abortion
  • The chance of preeclampsia is multiplied by 5
  • There is a 10 times greater chance of premature labor
  • The risk of heart failure is multiplied by 20
  • There is up to 10 times more risk of thyroid storm
  • Increased risk of early detachment of the placenta
  • More possibilities of suffering venous thrombosis
  • This disease also poses risks to the baby. There may be fetal death, stunted growth, neonatal goiter, congenital disabilities, and low birth weight.

Treatment and follow-up

Hyperthyroidism for the pregnant woman represents risks and the fetus, which also suffers its consequences.

The basic treatment is usually carried out with antithyroid drugs. However, it is always necessary to do a previous analysis of each woman’s specific health condition to prevent adverse effects on her or the fetus.

Antithyroid medications have teratogenic reactions, especially in the first trimester of pregnancy. The use of some of them has been associated with certain malformations and health problems in the fetus. Therefore, it is appropriate to follow closely to stop the medicine as soon as possible.

Almost always, the goal of treatment is to keep thyroid hormone levels as close to normal ranges as possible. If there are very adverse drug reactions, surgery should be considered as the last alternative.

The optimal time to perform the surgical procedure is the second trimester of pregnancy. Anyway, after thyroidectomy, it is necessary to continue with antithyroid medications.

Do not neglect thyroid control during pregnancy.

Thyroid abnormalities occur more frequently in women of childbearing age. Therefore, this is one of the aspects to evaluate during pregnancy.

If the problem is present, it is essential to detect it early, since the consequences of inadequate treatment can be very serious for both the mother and the child. For this reason, prenatal controls and gestation planning as early as possible are essential to reduce risks.