In others, however, the thyroid is more severely damaged. As noted in the figure, this phase usually begins anywhere between the third and eighth postpartum month. Postpartum thyroiditis was first described in the late 1940s. By the mid to late 1970s, it was infrequently mentioned in the medical literature. In the 1980s, however, it became clear that it was a common disorder.
Several possibilities exist.
One is that the disease is so mild that symptoms do not occur, and it spontaneously resolves. A second is that women are aware of symptoms, but neither they nor their physicians attribute them to a thyroid problem. We now know that some women do have mild symptoms of fatigue or depression three to six months after delivery, which is due to hypothyroidism. These symptoms may improve with thyroid hormone treatment. This condition must be distinguished from the most common form of hyperthyroidism known as Graves' disease, which also may have its onset after delivery.