The objective of this chapter is to present common thyroid disorders encountered in pregnancy will be addressed through case discussions. Thyroid disorders are the most common endocrine disorders in pregnancy after diabetes. Primary hypothyroidism is defined as inadequate thyroid hormone synthesis due to disorder of thyroid gland. Secondary or central hypothyroidism which is rare is due to disease in the pituitary gland or hypothalamus which results in inadequate production of thyrotropin or thyroid stimulating hormone. The best test to evaluate the thyroid function in pregnancy is a serum thyroid stimulating hormone (TSH). Hyperthyroidism in pregnancy can be caused by toxic multinodular goiter, solitary autonomously functioning nodule and Graves’ disease. Thyroid nodules are lesions in the thyroid gland which can be identified as separate from the surrounding thyroid tissue. In women with normal TSH, thyroid fine needle aspiration biopsy/cytology (FNA) is a safe and reliable procedure to evaluate thyroid nodules. Postpartum thyroiditis (PPT) is an autoimmune thyroid disorder that presents during the first postpartum year. PPT is treated symptomatically with beta- blockers in patients who have palpitations.