Does pregnancy affect the thyroid gland?

Yes: Hcg, a pregnancy hormone, stimulates the thyroid gland mildly, and some of the steroid hormones, like estradiol, increase thyroid binding proteins. Blood flow through the thyroid gland increases in pregnancy. The thyroid gland tends to work harder in pregnancy and needs more support. Iodine needs may be higher, and thyroid hormone levels should be monitored.

Yes: Gland size increases through the 9m function though usually stays normal, but in some, can get over or under production of thyroid hormone.