What are the “three thyroid function tests” during pregnancy?

The “Three Thyroid Function Tests in Pregnancy” is one of the most commonly used and routine screening methods during pregnancy.

What Are the “Three Thyroid Function Tests in Pregnancy”?

These three tests assess thyroid function in pregnant women and include: thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4). They are primarily used to evaluate whether a pregnant woman’s thyroid function is normal. During pregnancy, hormonal fluctuations are pronounced and may lead to endocrine imbalances. Untreated hypothyroidism or hyperthyroidism can adversely affect fetal development. Conducting thyroid function testing at this time helps detect abnormalities early, enabling prompt intervention and minimizing potential adverse effects on the fetus.

If FT3 and FT4 levels are significantly elevated while TSH is markedly suppressed, and the pregnant woman exhibits symptoms such as irritability, heat intolerance, and unintentional weight loss, she may have hyperthyroidism. For mild cases, iodine intake should be carefully controlled and regular monitoring performed. In severe cases, fetal development may be compromised, potentially resulting in congenital anomalies. Treatment with antithyroid medications—such as propylthiouracil—under physician supervision is recommended.

Conversely, if FT4 is decreased and TSH is significantly elevated, the pregnant woman may develop symptoms including edema, palpitations, and shortness of breath—indicative of hypothyroidism during pregnancy. This condition increases the risk of miscarriage, stillbirth, intrauterine growth restriction, and impaired neurodevelopment in the fetus. Prompt medical evaluation and appropriate treatment—typically with levothyroxine sodium—are essential. We hope this information is helpful. Wishing you good health and happiness!