Thyroid Health in Pregnancy: Why Is It Important for Mother and Baby?

Thyroid Health in Pregnancy: Critically Important for a Healthy Pregnancy and Your Baby

A healthy pregnancy and a healthy baby are the greatest wish of every expectant mother. For this reason, in addition to routine blood tests performed in the early period of pregnancy, monitoring of thyroid hormones is vitally important for your baby's healthy development…

We asked our General Surgery Specialist at Hisar Hospital Intercontinental about the thyroid problems seen during pregnancy and what expectant mothers should pay attention to…

Our specialist, who stated that a known thyroid disease during pregnancy can adversely affect the health of the mother and baby, said: 'Every woman who wishes to become pregnant should first have her thyroid tests done, and they should be checked after pregnancy occurs. Especially those with a previous history of thyroid disease, those treated for hyperthyroidism, and those with a family history of goiter should be followed closely. Thyroid hormones are very important for the development of the baby's brain.'

Do thyroid function changes occur during pregnancy?

It is normal for the thyroid gland to undergo some changes in both its function and size during pregnancy, and these are not considered a disease. Human chorionic gonadotropin (hCG) secreted during pregnancy and estrogen can also affect thyroid hormones.

What are the hormonal changes in thyroid function during pregnancy?

Thyroid function test results performed during pregnancy must be evaluated taking pregnancy into account. Estrogen released during pregnancy and human chorionic gonadotropin (hCG) also affect thyroid hormones. hCG, which is high during the first 3 months of pregnancy, may cause a certain decrease in the TSH level. This decrease is temporary. Estrogen, whose blood level rises during pregnancy, increases the proteins that bind thyroid hormone. As a result, an increase in the total thyroid hormone level is observed. 99% of the thyroid hormone in the blood is bound to these proteins. However, there is no increase in the free forms of thyroid hormones. Women whose TSH, free T3 (sT3) and free T4 (sT4) levels are normal throughout pregnancy means their thyroid gland is working normally.

Do thyroid gland size changes occur during pregnancy?

Growth in thyroid gland size may be observed during pregnancy. This may be more frequent and more pronounced, especially in regions with iodine deficiency. The enlargement of the thyroid gland during pregnancy is only around 10-15%, and it generally cannot be noticed as goiter with the naked eye. The most accurate assessment can be made with ultrasonography. True goiter or thyroid dysfunction may also be seen during pregnancy. These need to be evaluated by distinguishing them from normal or expected changes.

What are the causes of hypothyroidism in pregnancy?

Hypothyroidism, characterized by low levels of thyroid hormones in the blood, is normally most commonly caused by Hashimoto's thyroiditis in adulthood, so most cases of hypothyroidism during pregnancy are attributable to this pathology. This may be a newly starting Hashimoto's thyroiditis during pregnancy, or it may appear as a worsening of a previously known disease. In pregnancy, as in normal times, TSH monitoring is performed taking into account a slightly elevated TSH level.

What are the harms of hypothyroidism during pregnancy to the mother and baby?

Undetected or untreated hypothyroidism during pregnancy, i.e., decreased thyroid hormones in the blood, can occur without any symptoms and may lead to anemia in the mother, heart failure, placental abnormalities, muscle weakness, bleeding during labor, and giving birth to a low birth weight baby. Thyroid hormones are very important for the baby's brain development. In babies with congenital hypothyroidism, severe perceptual and mental disorders as well as neurological and developmental abnormalities may occur. If diagnosed immediately after birth, all of these adverse outcomes can be prevented. Today, thyroid hormones are checked by taking a blood sample from every newborn. If necessary, permanent problems can largely be prevented by administering thyroid hormone. Although how maternal hypothyroidism affects the baby's brain development is not fully known, developmental delay is frequently seen in the babies of mothers with hypothyroidism due to iodine deficiency. For this reason, thyroid hormones and TSH should be monitored before pregnancy and during pregnancy, especially in the risk group. This is because thyroid hormone requirement increases by 20-25% during pregnancy. Therefore, the medication doses of patients receiving drug therapy may sometimes need to be increased up to double. During pregnancy, thyroid tests should be checked at 6-8 week intervals. If the thyroid hormone dose is changed, the next check is done 4 weeks later. So-called prenatal vitamins, which are given for support during pregnancy and contain iron, reduce the absorption of thyroid hormone, so they should be taken with a 2-3 hour gap between the two medications. After delivery, the mother's medication requirement will decrease and pre-pregnancy doses will be returned to in a short time.