Analysis: Iodine is essential for a baby's brain development during pregnancy, but a new study has found low levels of the micronutrient in pregnant Irish women
Nutrition plays a key role during pregnancy, supporting both maternal wellbeing and the healthy development of the baby. While the importance of nutrients like iron and folic acid is well known and widely discussed, there is a greater awareness needed of the role iodine plays in pregnancy.
Iodine is a micronutrient that supports the production of thyroid hormones, which are essential for a baby's brain development during pregnancy. During pregnancy, the body’s requirement for iodine increases by about 50%, making it especially important to pay attention to intake during this time. Our bodies can't make iodine, so we need to get it from our diet. The main sources of iodine in the Irish diet are milk and yoghurt, white fish and eggs.
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But our research has found that 60% of pregnant women had insufficient iodine intake. The study involved over 1,500 first time mothers attending Cork University Maternity Hospital and the results were insightful.
The World Health Organisation (WHO) recommends an average urinary iodine concentration (UIC) of at least 150 micrograms per litre (µg/L) in pregnant groups. However, the average UIC in the study group was 125 µg/L, slightly below the recommended level.
Certain groups, including women who were younger, had a higher BMI, had lower education levels or were not taking iodine containing supplements, were more likely to have lower iodine levels. Seasonal variation also played a role, with slightly lower iodine levels observed in the summer months. Interestingly, two thirds of participants said they were taking supplements that contained iodine, yet many still had low levels. This suggests that supplement use alone may not guarantee adequate intake and highlights the importance of increased nutritional awareness to support maternal and child health.
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What does this mean for pregnant women?
Ireland does not currently have a policy for salt iodisation or iodine food fortification. Instead, national clinical practice guidelines recommend that pregnant women aim to get enough iodine from food, and from supplements where needed.
The HSE advises women who are planning a pregnancy to include iodine rich foods in their diet, such as milk and yoghurt (at least two servings daily) and white fish (once a week).
For women following vegan or plant-based diets, it’s recommended to choose iodine fortified alternatives. It’s important to be cautious with kelp or seaweed supplements, which can contain high levels of iodine and can potentially cause issues for the thyroid. Therefore, these are not recommended as a safe or reliable source of iodine during pregnancy.
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From RTÉ Radio 1's Morning Ireland, Four out of five pregnant women in Ireland are iron deficient by third trimester according to new research
'Valuable new evidence'
This study provides valuable new evidence that can help shape future clinical and public health policies. As the first large scale assessment of iodine status among pregnant women in Ireland, it offers a strong foundation for updating nutritional guidelines and raising awareness.
Iodine deficiency remains one of the most common micronutrient deficiencies worldwide, yet public understanding of its role in pregnancy, particularly in supporting brain development remains limited. Addressing this knowledge gap through education, dietary guidance, and potential policy review could help improve outcomes for both mothers and babies.
As we continue to learn more about the specific nutritional needs during pregnancy, simple, practical steps can make a real difference. These include incorporating iodine-rich foods like dairy and white fish into the diet and discussing supplement choices with a healthcare professional. For those following plant-based diets, choosing iodine-fortified products is particularly important.
This research project was supported by a Starting Investigator Research Grant from Research Ireland and forms part of ongoing work at the INFANT Research Centre and the Cork Centre for Vitamin D & Nutrition Research at UCC.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
