Physiological Changes of the Thyroid Gland Function in Pregnancy

The literature data regarding changes in thyroid function during pregnancy were analyzed. There has been described a number of factors (increased levels of human chorionic gonadotropin, estrogen, changes in deiodination processese, the need for iodine, etc.) influencing the synthesis of free and bound fractions of thyroid hormones. Characteristic differences of the above data in different trimesters of pregnancy are presented. It is shown that some pregnant women may have thyroid hormone levels beyond the normal range. According to the literature, in 9.7–30 % of women, thyroid-stimulating hormone level does not meet the trimester-specific intervals. The intense functioning of the thyroid gland in the mother increases the risk of pathological changes in it, and a violation of its functions is the risk of thyroid disease in the fetus too. In view of the above, timely diagnosis of thyroid function, control of the activity of adaptive processes in the pituitary-thyroid system in pregnant women are important