Thyroid dysfunction is the second most common endocrine disorder among women of childbearing age. When thyroid dysfunction is well controlled, pregnancy outcomes are similar to those of women without thyroid disease. Perinatal nurses can support the woman affected by a thyroid dysfunction by being knowledgeable about the disorder and by providing support and education. The article provides an introduction to the physiology and pathophysiology of the thyroid, the effect of common thyroid disorders on pregnancy, and clinical management implications for perinatal nurses.