Neonatal Thyroid Function Born to Mothers Living With Long-term Excessive Iodine Intake From Drinking Water
Optimal iodine nutritional status during pregnancy is essential for maintaining both proper thyroid function in mothers and normal development of the brain of progeny during foetal and early post-natal life. As neonatal thyroid function has not been established in the early trimester of pregnancy, so the growth and development of the foetus mainly rely on maternal thyroid hormones.[1] Because iodine is essential for the synthesis of thyroid hormones, iodine deficiency in the mother may lead to insufficient thyroid hormone synthesis in mothers and foetus, resulting in the impairment of the neuropsychological development in infants.[2,3] Therefore, the iodine requirement of the mother during pregnancy and lactation is increased. The daily iodine intake during pregnancy recommended by World Health Organization/United Nations Children's Fund/The International Council for the Control of Iodine Deficiency Disorders (WHO/UNICEF/ICCIDD) was 200 μg in 1996 and 250 μg in 2007.[4] In recent years, there have been increasing concerns about pregnant and lactating women and their weaning infants who do not receive sufficient iodine. The problem even exists in those countries that have sufficient iodine supplies for several decades.[5,6] The American Thyroid Association and The Endocrine Society recommend that pregnant and lactating women in North America where mild iodine deficiency is common should ingest an iodine supplementation containing 150 μg iodine per day while the total iodine intake not exceeding 500 μg/day.[7,8]
