Pregnant woman taking excessive amounts of iodine in the form of supplements promotes hypothyroidism in her baby, reports The Journal of Pediatrics.
Congenital hypothyroidism (hypothyroidism), as the name suggests, manifests itself with a deficiency of the thyroid hormone at birth. If left untreated, it can lead to disorders of the nervous system and mental development of children.
The World Health Organization (WHO) recommends that pregnant women take 200-300 micrograms of iodine daily per day to maintain normal fetal thyroid hormone production. The US Institute of Medicine considers 1100 micrograms the upper limit of safety.
Dr. Kara Connelly’s team described three thyroid-deficient infants whose mothers consumed 12,5 mg of iodine daily during pregnancy and nursing, which is 11 times the proposed upper limit of normal. Iodine enters the unborn baby’s body through the placenta and, after birth, through the mother’s milk. In the three examined children, the level of iodine in the blood was 10 times higher than in the control group of healthy infants.
Excess iodine causes a temporary suppression of the functioning of the thyroid gland, which avoids the excess of thyroid hormone (Wolff-Chaikoff effect). In adults and older children, this effect disappears after a few days, while fetuses and infants have not developed an appropriate mechanism, which in the case of chronic exposure to a high dose of iodine will expose them to hypothyroidism due to excess iodine.
Supplements, vitamin preparations and seaweed can be a source of large amounts of iodine in the diet. According to the authors of the research, pregnant women should consult their doctor about taking additional doses of iodine. (PAP)
pmw/ ula/