The fetus is completely dependent on the thyroid hormones provided by the mother in early pregnancy for normal brain development. Adequate daily iodine intake by the mother-to-be throughout pregnancy is essential to ensure the production of thyroid hormones, which also affects the establishment of normal thyroid function and normal brain and nerve development of the baby. During breastfeeding, breastfed babies are also totally dependent on the mother’s milk for iodine nutrition. Therefore, the iodine nutritional status of mothers-to-be and nursing mothers is very important. It is recommended that all mothers-to-be have an iodine nutritional test when planning a pregnancy or when they first find out they are pregnant. If iodine intake falls below 250 micrograms per day (i.e., urine test results show iodine concentrations below 150 micrograms/L in urine), a daily iodine supplement of 150 mg should be taken – this is the dose recommended by the World Health Organization for pregnant and lactating women. Mothers-to-be or nursing mothers with pre-existing thyroid conditions should consult their doctor before taking iodine supplements. 1. Why do pregnant and breastfeeding mothers need iodine in particular? Iodine is a nutrient that we need in very small but essential amounts. In our neck, there is a gland called the thyroid gland, which needs iodine to produce thyroid hormones. These hormones are necessary for proper brain and neurological development of the fetus, the baby, and the little ones. Therefore, it is very important to make sure that mothers-to-be and those who are breastfeeding receive enough iodine. Our body stores iodine in the thyroid gland, and since the reserves are very limited, any little use above the normal amount will result in a deficiency. 2. How much iodine do pregnant and lactating women need? The World Health Organization recommends that pregnant and lactating women take a daily oral iodine supplement to ensure adequate iodine intake (ensuring a daily iodine intake of 250 micrograms). Pregnant and lactating women need to maximize their iodine intake because their iodine needs increase during pregnancy and lactation, and they may not get enough iodine from iodine-fortified foods and their daily diet. 3. What foods contain iodine? The majority of foods in China contain only very small amounts of iodine, which makes it difficult for pregnant and lactating women to get enough iodine from food. Seasonal variations and differences in production processes, etc. can cause iodine levels in foods to vary widely. Iodized salt and seafood are the main sources of iodine in Chinese food. In the interior of China, however, only iodized salt is the main source in food. 4. Why do pregnant and lactating women need more iodine than normal people? Humans store the acquired iodine in the thyroid gland. During pregnancy, the thyroid gland becomes particularly active, producing 50% more thyroid stimulating hormones than usual. In order to produce more thyroid hormones to support the mother and the fetus, the pregnant mother needs to increase her iodine intake. If the iodine intake is not sufficient before pregnancy, the mother’s iodine stores will not be sufficient to meet the needs of her unborn baby during the later stages of pregnancy. The production levels of thyroid hormones will return to normal levels during the lactation period. However, it is still recommended that breastfeeding women continue to take iodine supplements because breastfed children rely exclusively on breast milk as a source of iodine acquisition, and children need 90 to 100 mg of iodine daily. The infant will use this iodine to build and store his/her own thyroid hormones. 5. Do pregnant and breastfeeding mothers in China get enough iodine? A partly not. According to WHO standards, the Chinese are considered iodine deficient, which is why we need to use iodized salt. Research on maternal iodine levels in China is more limited, but from the available previous fortification additions show that many Chinese mothers are iodine deficient. Regardless of the large regional differences in salt intake, a national average of 218-327 mcg/day is necessary and safe, and the WHO recommends 250 mcg/day for pregnant and lactating women. Therefore, at this average salt intake level, and not taking into account any iodine loss during cooking, there is still a high probability that pregnant and lactating women in China are iodine deficient, assuming that all the iodine in salt is effectively consumed. 6. What can happen if pregnant and lactating mothers are iodine deficient? The most significant health concern regarding maternal and lactating women who are iodine deficient is that this may negatively affect the brain and neurological development of the unborn baby, the newborn infant, and in particular can reduce the child’s intelligence. When iodine intake is lower than the recommended intake, the thyroid gland fails to produce sufficient thyroid hormones and a range of iodine deficiency dysfunctions may occur. Iodine deficiency during pregnancy is of particular concern because abnormal thyroid function in the mother can negatively affect the fetal nervous system and increase infant mortality. Damage to the brain and nervous system early in development is usually irreversible and can have a serious impact on the intelligence of the child in the future. 7. After consuming iodized salt, do pregnant and lactating women need to take additional iodine supplements? Yes. To protect public health, all salt on the market in China is iodized salt. By mandatory addition, most people will get enough iodine, which means that women of childbearing age are getting enough iodine until they enter pregnancy. However, the iodine in iodized salt plus the iodine in food in many areas of China is not enough to provide the additional iodine needed during pregnancy and lactation. Pregnant mothers whose iodine intake is below 250 micrograms per day, i.e. urine test results of less than 150 micrograms/L of iodine, should take 150 mg of iodine supplements daily. During breastfeeding, a portion of the iodine enters the breast milk and is given to the baby through the breast milk. A nursing mother who detects a urine iodine level below 100 micrograms/L also needs iodine supplementation. 8. Is taking iodine supplements safe for all women? It is safe for most women, but a mother with pre-existing thyroid disease should consult with her doctor before taking iodine supplements. 9. If I take iodine supplements, will pregnant or nursing mothers get too much iodine? No. Taking the recommended 150 mcg/day of iodine supplements will not result in an iodine overdose. For those mothers who are worried that they will overdose on iodine if they already take iodized salt, let’s do a simple elementary school arithmetic. You need 150 micrograms of iodine per day on a regular basis, and let’s say that through table salt and your food, you are getting an average of 200 micrograms of iodine per day. You are healthy and have no thyroid disease. Your intake is greater than your need to ensure that you meet your need, and your intake is 50 micrograms higher than your need. That’s good. During pregnancy and lactation, you need to consume 250-270 micrograms of iodine per day to have enough iodine to meet the needs of your fetus/infant. Your needs, now, are about 100-120 mcg higher than before. You are still getting 200 micrograms in your diet. You get an additional 150 mcg of iodine through supplements, and the extra portion of your intake is only 30-50 mcg up from the portion needed by the fetus/baby to ensure that you can meet the fetal needs. Your current intake of 150 (supplements) + 200 (food) = 350 mcg is still 50 (50 more to ensure you meet your own needs) + 50 (to ensure you meet the needs of the fetus) mcg higher than your needs. In other words, if your pre-pregnancy iodine intake was not excessive, then you would not be overdoing it by supplementing with an additional 150 micrograms of iodine during pregnancy and lactation. You take iodized salt before pregnancy, and you need the same during pregnancy, and you need about 150 micrograms more. It is also important to know that the dangers of insufficient iodine are far greater than the dangers of too much. There are many studies that show that if there is an excess of iodine, the side effects of excess iodine disappear when the intake is lowered. 10. Are there any sources of iodine that should not be taken by pregnant women, nursing mothers or women preparing to become pregnant? There are. Algae (kelp, seaweed, seaweed) or algae products should not be taken as an iodine supplement during pregnancy or lactation. This is because they are very unstable in terms of iodine content and may contain heavy metals such as mercury. The iodine content of raw oysters in seafood is also relatively high, but special care should be taken with any seafood in the shell during pregnancy to avoid bacterial or viral infections. Therefore, mothers are advised to take supplements (multi-nutrient tablets) designed for pregnancy and lactation and should check that your vitamin and mineral supplements contain the recommended levels of iodine, preferably in supplements specifically designed for pregnant and lactating women. 11. At what point should I start and end iodine supplementation? Mothers whose iodine intake is less than 250 micrograms per day, i.e. women whose urine test is below the level 150 micrograms/L, should start iodine supplementation from the time they plan to become pregnant and continue throughout pregnancy and lactation. In the case of an unplanned pregnancy and if the iodine intake is found to be insufficient, the mother-to-be should start iodine supplementation as soon as possible after the pregnancy is discovered. 12. Iodine supplementation for mothers in other countries Mothers who live on the coast can also supplement iodine because you are only supplementing the portion needed by the fetus. In Australia, government mandated iodization is not through table salt, but through bread. In a country where almost all cities are near the sea and consume a lot of seafood, the National Institute for Health and Medical Research has recommended since 2010 that all pregnant and nursing mothers in the country take 150 micrograms of iodine per day (those with thyroid abnormalities need to consult a doctor first). In the U.S. and Canada, although most pregnant mothers are adequately nourished with iodine, a small percentage are still iodine deficient, and the government continues to recommend that mothers-to-be throughout the U.S. and Canada take a supplement suitable for pregnancy and lactation that contains 150 mcg of iodine daily and that they take it from pregnancy until the end of lactation.