[Autoimmune thyroid disease and pregnancy--challenge or routine].

TSH or Thyroid Stimulating Hormone, is responsible for regulating the amount of thyroid hormones released by the body. The TSH is produced by the pituitary gland. If there is a thyroid problem or the thyroid gland is diseased, it may result in excess or reduced production of thyroid hormone, and these conditions are called hyperthyroidism and hypothyroidism respectively. Normal thyroid function is needed for a successful pregnancy. In the general population, a TSH level between 0.45 and 4.5 mIU/l is considered normal and indicates euthyroidism. Studies, however, have suggested that the normal TSH level during pregnancy should be lower than this and have suggested using 2.5 mIU/l as the upper range cutoff. The risk for miscarriage and preterm delivery were increased when the level was higher. The presence of thyroid antibodies may further complicate this situation. Women with positive antibodies are at a 2-fold increased risk for miscarriage.