WHY Iodine Is Critical During Pregnancy and Breastfeeding

Iodine is critical during pregnancy as adequate intake is essential for the synthesis of maternal thyroid hormones.

The thyroid hormones produced by the mother help the body cope with the metabolic demands of pregnancy, and ensure healthy development of the brain, and nervous system of the unborn baby.

Research shows even a mild iodine deficiency can lead to children born with a lower intelligence quotient (IQ). Consequently, women who are pregnant or considering having a baby should ensure they get enough of this vital nutrient.

Why Iodine is Critical During Pregnancy

Pregnancy is a time when great physiological stress is placed on both the mother, and the developing baby.

You may be surprised to learn that during pregnancy the thyroid is particularly active, and produces about 50% more thyroid hormones than usual. This is why adequate maternal iodine stores are critical during pregnancy.

Iodine For Breastfeeding Women

Iodine requirements remain elevated during breastfeeding as this nutrient is vital for the baby to continue to grow and develop properly.

The iodine concentration of breast milk can be vary greatly depending on how much iodine the mother is getting from her diet or nutritional supplements.

Seafood, and sea vegetables are naturally rich in iodine. Other food sources include iodized salt and plant based foods grown in nutrient rich soil. However due to variable soil quality most foods grown in Australia contain only trace amounts of iodine. This puts women at risk of low iodine intake when they need it most.

It’s important to note that due to safety concerns pregnant women are advised not to consume shellfish during pregnancy.

Declining Dietary Intake of Iodine

According to a worldwide survey by the World Health Organization (WHO) iodine deficiency is the leading cause of hypothyroidism, the term used to describe a drop in thyroid hormone production. Hypothyroidism affects both industrialized and developing nations.

Due to the important role iodine plays in pregnancy the National Health and Medical Research Council (NHMRC) of Australia recommends a daily intake of 220 micrograms (μg) of iodine per day for women who are pregnant, or considering pregnancy. While breastfeeding the recommendation increases to 270 micrograms (μg) per day.

Iodine supplements are generally considered safe when taken as recommended. They are a convenient way to help ensure adequate iodine intake. However, it’s important to seek advice from your doctor before making any changes to your diet, exercise routine, or supplement protocol, especially if you have a diagnosed thyroid disorder. Your doctor can make recommendations that are best for your overall health.


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Li M, Ma G, Boyages SC, Eastman CJ. Re-emergence of iodine deficiency in Australia. Asia Pac J Clin Nutr. 2001;10(3):200-3.

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National Health and Medical Research Council (NHMRC). Nutrition Reference Values for Australia and New Zealand. Iodine. www.nrv.gov.au/nutrients/iodine.htm.

National Health and Medical Research Council (NHMRC). Iodine supplementation for Pregnant and Breastfeeding Women. http://www.nhmrc.gov.au/guidelines/publications/new45. 2010.

Renner R. Dietary iodine: why are so many mothers not getting enough? Environ Health Perspect. 2010;118.

Zimmermann MB. Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review. Am J Clin Nutr. 2009 Feb;89(2):668S-72S.


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