Iodine and Pregnancy: An Essential Nutrient for Maternal and Fetal Health

Why Do You Need Iodine?

Iodine is crucial for the normal functioning of the thyroid gland, as it is a key component of thyroid hormones, including triiodothyronine (T3) and thyroxine (T4). These hormones are vital for various biological functions throughout the body, as almost all organs and tissues contain cells sensitive to thyroid hormones.

Thyroxine and triiodothyronine influence metabolism, tissue sensitivity to other hormones, body temperature regulation, protein synthesis, growth and development, blood pressure, heart rate, oxygen utilization, and the metabolism of vitamins and glucose. The importance of iodine cannot be overstated; without adequate iodine intake, the synthesis of these hormones is compromised.

Sources of Iodine

Iodine is present in drinking water and various food products, but accurately determining iodine content in these sources can be challenging. The iodine levels in water depend on factors like soil composition, proximity to saltwater, altitude, and acidity. For instance, rainwater on the coast contains significantly more iodine than that collected inland.

Plant and animal iodine content correlates with the iodine levels in the soil where they are grown or grazed. Foods rich in iodine include seafood, seaweed, and certain dairy products. Coastal populations that consume seafood regularly rarely experience iodine deficiency. However, approximately 2 billion people worldwide live in areas with iodine deficiency due to insufficient dietary intake.

Preventive measures for iodine deficiency include using iodine-containing supplements, iodized salt, and fortified foods.

How Much Iodine Do You Need?

According to the European Food Safety Authority and the U.S. National Academy of Medicine, the optimal daily iodine intake for adults is 150 mcg. Recommendations for children vary by age:

• Infants (0-12 months): 110-130 mcg/day
• Children (1-8 years): 90 mcg/day
• Children (8-13 years): 130 mcg/day
• Teens (13-18 years): 150 mcg/day

Increased Iodine Requirements During Pregnancy

The need for iodine significantly increases during pregnancy and breastfeeding. Pregnant women require 220 mcg of iodine daily, while nursing mothers need 290 mcg. This increased demand is due to the physiological changes during pregnancy and the need to support both maternal and fetal thyroid function.

In the first trimester, when the fetus's thyroid gland is not yet fully developed, adequate iodine intake is critical for the normal development of the baby's nervous system and brain.

Consequences of Iodine Deficiency During Pregnancy

Iodine deficiency during pregnancy can lead to serious health issues, including:

• Increased risk of miscarriage and preterm birth
• Infant mortality
• Growth and developmental disorders in the child
• Irreversible intellectual disabilities and lower IQ

Despite the ease of prevention, iodine deficiency remains the most common preventable cause of intellectual disabilities globally.

Risk Factors for Iodine Deficiency

Several lifestyle factors can increase the risk of iodine deficiency during pregnancy, including:

• Smoking
• Adopting a vegan diet
• Using non-iodized salt
• Lack of dairy and seafood in the diet

Pregnant women with these risk factors should pay special attention to their iodine intake, particularly during the planning stages of pregnancy.

Preventing Iodine Deficiency

Most healthcare professionals recommend that pregnant and breastfeeding women take a daily multivitamin or prenatal supplement containing 150 mcg of iodine. It is advisable to start this supplementation three months before conception.

For non-pregnant women, assessing the diet, use of iodized salt, and the iodine content in drinking water can help determine the necessity for iodine supplementation. However, during pregnancy, the consequences of iodine deficiency are severe, making an additional daily intake of 150 mcg advisable.

Important Considerations:

Not all prenatal vitamins contain iodine, and those that do may not provide the required amount. Always check labels and consult with a healthcare provider.

Are You Planning a Pregnancy? Are You Pregnant? Are You Breastfeeding? Make sure to take 150 mcg of iodine daily!

Note: 1 mcg is one-millionth of a gram. A daily intake of 150 mcg is a small amount, yet it plays a crucial role in preventing significant health issues.

References: 

1. O'Keeffe M, De Regil LM, Bennett A, et al. Iodine supplementation for women during pregnancy. Cochrane Database Syst Rev. 2016;2016(2)
   . doi:10.1002/14651858.CD011761.pub2
2. World Health Organization. Iodine in pregnancy: A systematic review of the evidence. Available at: https://www.who.int/tools/elena/bbc/iodine-pregnancy. Accessed October 10, 2024.
3. Venn-Watson S, McKinney M, Smith K, et al. Iodine supplementation during pregnancy: Are we doing enough? Nutr Rev. 2016;74(4):267-277. doi:10.1093/nutrit/nuw005
4. Centers for Disease Control and Prevention. Iodine: Diet and micronutrients during breastfeeding. Available at: https://www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/diet-and-micronutrients/iodine.html. 
5. O'Keeffe M, De Regil LM, Bennett A, et al. Iodine supplementation for women during pregnancy: An update. Cochrane Database Syst Rev. 2018;2018(3)
   . doi:10.1002/14651858.CD011761.pub2
6. Cakmak B, Hecimovic M, Ilekovic D, et al. Iodine status and iodine intake in pregnant women: A cross-sectional study in the northern area of Croatia. Public Health Nutr. 2015;18(6):1058-1067. doi:10.1017/S1368980014001518