“Iodine is one of the essential trace elements in the human body and is closely related to the function of the thyroid gland. Insufficient iodine intake can cause iodine deficiency diseases, and iodine deficiency during pregnancy can lead to miscarriage, stillbirth, and congenital malformations. Iodine deficiency in infancy can lead to hypothyroidism, neuromotor failure, mental retardation, and cretinism, while iodine deficiency in adulthood can lead to goiter and other complications. Are pregnant women in China iodine deficient? China is one of the countries with the most serious iodine deficiency disease epidemic in the world, and pregnant women and children are at high risk of iodine deficiency. Pregnant women need the thyroid gland to take in more iodine to synthesize more thyroid hormones to maintain normal physiological functions due to the increase in circulating blood volume and changes in placental hormone levels. In addition, the fetus has the ability to synthesize thyroid hormones in the middle of pregnancy, which increases the mother’s demand for iodine. Therefore, iodine deficiency during pregnancy not only affects the mother’s own physiological status, but also is detrimental to the normal development and growth of the baby, and may even lead to irreversible brain development delay in the fetus (e.g. endemic cretinism). What is a normal iodine level? The normal iodine nutrition level of pregnant women should be in a state of positive physiological equilibrium, i.e., the total daily iodine intake is greater than the daily excretion. The main route of iodine excretion in the body is through urine, which accounts for 85%-90% of the total iodine excretion. Since the daily iodine absorption and utilization of the body is constant, the daily urinary iodine excretion basically reflects the iodine intake of the day. Therefore, urinary iodine excretion can be used to indirectly determine the iodine intake status. The World Health Organization, the United Nations Children’s Fund and the International Council for the Control of Iodine Deficiency Disorders jointly recommend a normal range of 150-249 μg/L (median) for urinary iodine in pregnant women. The results of the national iodine nutrition monitoring in 2013 and 2014 showed that the median urinary iodine level of pregnant women in most areas was less than 150μg/L. The iodine nutrition status of pregnant women needs to be improved. For the health of you and your unborn child, you can assess your iodine nutrition status through urine iodine testing during your maternity checkup. A test result below 150 μg/L indicates a possible iodine deficiency and a comprehensive iodine nutritional assessment is recommended. If iodine deficiency is confirmed, it can be corrected through dietary interventions. How can dietary interventions be performed for iodine deficiency? Pregnant women with iodine deficiency first need to consume iodized salt on a daily basis and supplement with iodized salt for pregnant women if necessary. You can also supplement iodine-rich foods in moderation: seafood such as nori, scallops, jellyfish, kelp, sea cucumber, etc. 1-2 times a week is sufficient. Long-term consumption in large quantities may harden the thyroid gland, which may be easily mistaken for a thyroid tumor. Iodine has an important role to play in the health of pregnant women and fetuses, and iodine deficiency should be detected and treated effectively. Iodine deficiency should be treated effectively and promptly. Iodine deficiency should be supplemented, but iodine supplementation should be moderate. The reference daily intake of iodine for pregnant women in China is 230 μg/d, and the maximum tolerable intake is 600 μg/d. Excessive iodine intake can cause iodine overload, resulting in abnormal levels of thyroid stimulating hormone (TSH) and/or thyroid hormones (T3, T4), increasing the risk of thyroid disease. We can prevent excessive iodine intake by consuming iodine-rich foods with moderate amounts of soy products: e.g. tofu, natto, etc.