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Pregnancy 2023

Thyroid in pregnancy: main changesções (and care)

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Thyroid in pregnancy: main changesções (and care)
Thyroid in pregnancy: main changesções (and care)

The thyroid in pregnancy is important for the he alth of the mother and baby and any dysfunction must be identified and treated so as not to bring complications to the baby who needs the mother's thyroid hormones until approximately the 12th week of pregnancy. After this stage, the baby is able to produce its own thyroid hormones.

The thyroid hormones are T3, T4 and TSH that can be increased or decreased causing the main thyroid problems in pregnancy such as hypothyroidism and hyperthyroidism. These disorders can cause miscarriage, premature birth or influence the development of the fetus. In addition, thyroid dysfunctions can cause changes in the menstrual cycle, making it difficult to get pregnant.

Therefore, it is important to carry out preventive exams to get pregnant and prenatal care to diagnose hypothyroidism or hyperthyroidism, ensuring the he alth of the mother and baby. Find out which tests should be done when planning to get pregnant.

The main thyroid changes in pregnancy are:

1. Hypothyroidism

Hypothyroidism is the decrease in the production of thyroid hormones during pregnancy and can cause increased bleeding, miscarriage, premature birth or increased blood pressure and preeclampsia. Already in the baby, hypothyroidism can cause delay in mental development, cognitive deficit, decreased intelligence quotient (IQ) and goiter (chat).

The most common symptoms of hypothyroidism are drowsiness, excessive tiredness, weak nails, hair loss, decreased heart rate, constipation, dry skin, muscle pain and memory loss.

Hypothyroidism can also happen postpartum or a few months after the baby is born, requiring treatment. Learn more about hypothyroidism.

2. Hyperthyroidism

Hyperthyroidism is the increase in the production of thyroid hormones that, although not very common during pregnancy, can cause spontaneous abortion, heart failure, preeclampsia, placental displacement or premature birth in pregnant women. In the baby, hyperthyroidism can cause low birth weight, neonatal hyperthyroidism, or stillbirth.

The symptoms of hyperthyroidism in pregnancy are heat, excessive sweating, tiredness, fast heartbeats and anxiety, which often make diagnosis difficult, as these symptoms are common in pregnancy, but laboratory tests allow for a safe diagnosis and, thus,, start the best treatment. Learn more about hyperthyroidism in pregnancy.

Care during pregnancy

Some important precautions during pregnancy are:


Treatment of hypothyroidism in pregnancy is done with medications, such as levothyroxine, for example. It is important to take the medicine at the same time every day. However, if you forget to take a dose, take it as soon as you remember, taking care not to take two doses at the same time. Prenatal follow-up or consultations with an endocrinologist should be performed at least every 6 to 8 weeks to check thyroid hormone levels and, if necessary, adjust the drug dose.

In the case of hyperthyroidism in pregnancy, follow-up should be done every 4 to 6 weeks and routine ultrasounds should be performed on the baby. The treatment of hyperthyroidism in pregnancy should be started immediately after diagnosis and is done with medication such as propylthiouracil, for example, and the dose should be adjusted, if necessary.After delivery, you should inform your pediatrician that you had hyperthyroidism during pregnancy so that tests can be carried out on the baby and, thus, check if the baby also has hyperthyroidism and, if necessary, start treatment. See other 7 exams that newborns should do.


Food during pregnancy should be varied and balanced to provide the necessary nutrients for both mother and baby. Some foods contain iodine in their composition that is necessary for the production of thyroid hormones, such as cod, egg, liver and banana, helping to maintain thyroid balance. In cases of thyroid dysfunction in pregnancy, follow-up with a nutritionist is recommended in order to maintain a he althy diet. See more 28 foods rich in iodine.

Exams and Routine Consultations

It is important that women who have been diagnosed with hypothyroidism or hyperthyroidism during pregnancy are accompanied by a gynecologist-obstetrician or endocrinologist to monitor the development of the fetus and ensure the he alth of the mother and baby.However, if in the period between consultations you have symptoms of hypothyroidism or hyperthyroidism, seek medical attention immediately. Learn more about prenatal care.

During consultations, laboratory tests of the levels of T3, T4 and TSH hormones are requested to assess thyroid functioning and, if necessary, thyroid ultrasound. In case of any change, the most appropriate treatment should start immediately.

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