It is generally agreed that thyroid hypertrophy in women either starts as a congenital defect or begins at puberty or during pregnancy. These are very old observations. In Charpentier's Cyclopedia of Obstetrics and Gynecology, the American edition of which was published in 1887, there is a two page discussion of goiter and its influence on pregnancy. Under treatment, he says: "As goiter is generally benign during pregnancy, we should resort to general measures and internal treatment. Forbid the patient to nurse and give iodine." Moderate hypertrophy of the thyroid has been accepted as an incident of pregnancy, and until Marine's work most of us gave it little or no thought. Approximately 41 per cent of the last 520 patients I have examined in early pregnancy had some hypertrophy of the thyroid. While the hypertrophy that occurs during pregnancy is usually slight and, as a rule, transient, eight patients in this