In areas of severe deficiency, a large fraction of the adult population may show goiters. In such settings, overt cretinism may occur in 5 to 10 percent of offspring, and perhaps five times that many children will have mild mental retardation. This is a serious, tragic and, most importantly, a preventable problem. The fetus of an iodine-deficient mother can be successfully treated if iodine supplementation is given during the first or second trimester. Treatment during the third trimester or after birth will not prevent the mental defects.
Iodine deficiency can also be a sigificant problem in animal populations.
The most common manifestation in sheep, cattle, pigs and horses is a high incidence of stillbirths and birth of small, weak offspring. Hyperthyroidism in Pregnancy Gestational hyperthyroidism is associated with increased risk of several adverse outcomes, including preeclampisa, premature labor, fetal or perinatal death and low birth weight. In humans, hyperthyroidism usually is the result of Grave's disease, which involves development of autoantibodies against the TSH receptor that stimulate the thyroid gland. Timing of vulnerability of the brain to iodine deficiency in endemic cretinism.