Low Maternal Iodine Levels Can Hurt Fetal Intellectual Development

pregnant woman sitting on the couch drinking milk

Getty Images

Key Takeaways

  • Iodine helps fuel hormones essential for growth and development.
  • A new study notes that certain dietary practices can lead to iodine deficiency in pregnant moms.
  • Proper iodine levels are important for the fetus and for the mother.

Balanced nutrition is important for an expectant mother, to assure her baby receives all the nutrients it needs during gestation. Doctors emphasize getting the right vitamins and minerals, but the crucial nutrient of iodine can be overlooked.

A study published in the International Journal of Environmental Research and Public Health by researchers at the University of South Australia says that a lack of iodine intake by a pregnant woman can have devastating effects on her baby’s intellectual development.

Small Study Points in the Right Direction

This study compared the urinary iodine concentration of 31 women who consume vegan/plant-based diets and 26 women who also consume meat and dairy. While neither group hit the 100 micrograms per liter recommended by the World Health Organization, meat-eaters averaged 64 micrograms per liter, while the plant-based group averaged 44 micrograms per liter.

The way they got their iodine also made a difference. Participants who chose pink or Himalayan salt instead of iodized salt were extremely deficient, averaging only 23 micrograms per liter.

While 57 participants is a very small study population, the results suggest the need for larger studies.

“The study gives us a word of caution that sometimes good intentions can lead to some unintended consequences. So, [we must] make sure women that are pregnant are talking to their doctors during pregnancy, and they are sharing their health condition, their lifestyle choices, and medications they’re on. It’s really important to be very detailed in describing their diet,” notes Saima Aftab, MD, FAAP, Chief of Neonatology, Nicklaus Children’s Pediatric Specialists and VP for Organizational Initiatives, Nicklaus Children’s Health System. 

This pilot study is reminiscent of earlier research into iodine deficiency, and its informative results.

“A landmark study of 1,000 families in southwest England, published in The Lancet in 2013, showed that pregnant mothers who were deficient in iodine were more likely to have children with learning difficulties. They found that the women who had lower urinary iodine during pregnancy (indicating that they were mildly to moderately deficient in iodine) were more likely to have children with lower IQ scores at age 8, particularly in verbal and reading scores,” recalls Cindy Edouard, BSRRT, MPH.


Our Bodies Need Iodine

Because iodine is such a necessary element for development and the ongoing maintenance of vital organs, its absence leaves a huge and potentially dangerous void.

“When moms are pregnant, their requirement for iodine increases,” Dr. Aftab explains. “Sometimes we don’t find out that moms are not taking enough iodine until it’s much more advanced, and their numbers are already low,” Dr. Aftab states. “We sometimes don’t know a baby has low levels of iodine until way after birth, when the damage is done.”

Saima Aftab, MD, FAAP

We sometimes don’t know a baby has low levels of iodine until way after birth, when the damage is done.

— Saima Aftab, MD, FAAP

“If (a mother) is deficient in iodine and thyroid hormone both during pregnancy and during pre-conception, the baby risks mental impairment,” states Edouard. “Some babies have a yellow color to their skin or the whites of their eyes. This is called jaundice.”

The American Thyroid Association notes on its website that, “Thyroid hormones help the body use energy, stay warm and keep the brain, heart, muscles, and other organs working as they should.”

Babies aren’t the only ones affected by low levels. 

“Goiter, known for causing a large swelling of the neck where the thyroid gland is located, is typical of severe iodine deficiency,” Edouard states.

How Do You Make Sure You're Getting Enough Iodine?

Just as having a diet full of protein, folic acid and Vitamin C is important during pregnancy, so is a diet that contains iodine.

“The body does not make iodine, so it is an essential part of your diet,” notes the American Thyroid Association.

Fad diets that recommend limiting or removing certain nutrients are problematic if they create a deficiency. “The difficulty we have is sometimes we don’t find out about the impact or harm of these restrictive diets until much later,” Dr. Aftab explains.

She continues, “Recognize that when we have moms that are pregnant, we tell them, no alcohol, and smoking is bad for the baby. It’s (important) to make sure women recognize the importance of good nutrition, healthy eating and a balanced diet.”

Cindy Edouard, BSRRT, MPH

One simple way to ensure you get enough iodine is to check your prenatal vitamin—make sure it provides about 150 micrograms. It’s important not to overdo it; too much iodine can also be a problem.

— Cindy Edouard, BSRRT, MPH

Edouard adds, “One simple way to ensure you get enough iodine is to check your prenatal vitamin—make sure it provides about 150 micrograms. It’s important not to overdo it; too much iodine can also be a problem. Seafood, eggs, milk, and milk products are among the best sources of iodine. Vegans, people with certain food allergies or lactose intolerance, and others who consume no or minimal amounts of these foods might not obtain sufficient amounts of iodine.”

It’s even more important to get iodine from food sources, as there is no specific test to indicate an iodine deficiency. “We measure thyroid hormone as a surrogate marker for how well the mom’s thyroid is doing; just sort of a downstream byproduct to getting enough iodine,” Dr. Aftab notes.

Even With a Deficiency, There Is Hope

“The main treatment for (iodine deficiency) is thyroid hormone replacement. It is safe and easy to take. If it is begun immediately after your child is diagnosed, treatment can prevent many or all of the effects," Edouard advises. "If damage to the brain and nerves happens because treatment is delayed, it is usually permanent and cannot be reversed."

Monitoring iodine intake, eating a balanced diet, and attending prenatal visits from the start of pregnancy is the best way to plan for a healthy, happy baby.


What This Means For You

Prenatal visits and good prenatal nutrition are essential. As the study notes, iodine is a necessary part of that prenatal preparation. By ensuring that your body is getting all of the iodine it needs, you start your child on a healthier course. A little extra effort to take in the right nutrients can go a long way in making a difference in your baby’s life.

2 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Whitbread JS, Murphy KJ, Clifton PM, Keogh JB. Iodine excretion and intake in women of reproductive age in South Australia eating plant-based and omnivore diets: a pilot study. Int J Environ Res Public Health. 2021 Mar 29;18(7):3547. doi:10.3390/ijerph18073547

  2. Bath SC, Steer CD, Golding J, Emmett P, Rayman MP. Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC). Lancet. 2013;382(9889):331-337. doi:10.1016/S0140-6736(13)60436-5

By LaKeisha Fleming
LaKeisha Fleming is a prolific writer with over 20 years of experience writing for a variety of formats, from film and television scripts, to magazines articles and digital content. She has written for CNN, Tyler Perry Studios, Motherly, Atlanta Parent Magazine, Fayette Woman Magazine, and numerous others. She is passionate about parenting and family, as well as destigmatizing mental health issues. Her book, There Is No Heartbeat: From Miscarriage to Depression to Hope, is authentic, transparent, and providing hope to many.Visit her website at