An underactive thyroid gland results in hypothyroidism. Many pregnant individuals with Hashimoto's disease develop an underactive thyroid. Many women with Hashimoto's disease develop an underactive thyroid. If the goitre is associated with an underactive thyroid, thyroid supplements are used as treatment. Hashimoto's disease is the most common cause of an underactive thyroid. This is called an underactive thyroid or hypothyroidism (heye-poh-THEYE-royd-ism). An underactive thyroid needs to be treated. In some cases, an underactive thyroid may inhibit the production of breast milk. An underactive thyroid without symptoms occurs in 2 to 3 in every 100 pregnancies. The dorsolateral prefrontal cortex is especially underactive when a person suffers from chronic schizophrenia. It is included in the therapy for underactive bladder with poor contraction of detrusor muscle. The underactive regions included motor neurons that control face and mouth regions.