1. Goitre is an enlargement of the thyroid gland that can be congenital or acquired. It can cause the thyroid to function normally, be underactive (hypothyroidism), or overactive (hyperthyroidism).
2. The most common causes of congenital goitre are factors transmitted from the mother to the fetus during pregnancy that interfere with fetal thyroid function, such as antithyroid drugs or hyperthyroidism.
3. Hypothyroidism in infants is the most common cause of congenital hypothyroidism and occurs when the fetal thyroid system fails to develop correctly, resulting in mental retardation if not treated.