Abstract

THYROID FUNCTION IN PREGNANT WOMEN

Shahrazad Kamil Habeeb* and Raya Issa Rezqallah

Abstract

Two pregnancy-related hormones—human chorionic gonadotropin (hCG) and estrogen—cause increased thyroid hormone levels in the blood. Made by the placenta, hCG is similar to TSH and mildly stimulates the thyroid to produce more thyroid hormone. Increased estrogen produces higher levels of thyroid-binding globulin, also known as thyroxine-binding globulin, a protein that transports thyroid hormone in the blood. These normal hormonal changes can sometimes make thyroid function tests during pregnancy difficult to interpret. Thyroid hormone is critical to the normal development of the baby‘s brain and nervous system. During the first trimester, the fetus depends on the mother‘s supply of thyroid hormone, which comes through the placenta. At around 12 weeks, the baby‘s thyroid begins to function on its own. The thyroid enlarges slightly in healthy women during pregnancy, but not enough to be detected by a physical exam.

Keywords: Thyroid, pregnant women.