Iodine in Pregnancy, Breastfeeding and Infant Brain Development: Official Advice
What health bodies in the US, UK, EU and Canada say about iodine in pregnancy and breastfeeding, what trials found for babies, and why kelp products are a poor shortcut.
Content last updated . This page has not been medically reviewed.
Please read first. Pregnancy and breastfeeding raise iodine needs, but this page is not a personal plan. Whether you need an iodine-containing supplement depends on your diet, your thyroid health and your medicines, so ask your midwife, doctor or pharmacist. If you have thyroid disease or take thyroid medicine, ask before taking any iodine supplement. [1]
What official sources say
Figures are in micrograms (mcg) of iodine a day. Read the body, the year and the group before comparing.| Body, year | Group | What it says |
|---|---|---|
| US Dietary Reference Intakes, via MedlinePlus (reviewed 2025) | Pregnancy; breastfeeding | RDA 220 mcg; 290 mcg. Infants 0 to 6 months: Adequate Intake 110 mcg; 7 to 12 months: 130 mcg. [3] |
| American Thyroid Association (US and Canada), 2006 | Pregnancy and breastfeeding | Recommended, until more data were available, that women receive 150 mcg and that all prenatal vitamin and mineral preparations contain 150 mcg of iodine. [2] MotherToBaby (2025) describes the ATA advice as a daily supplement containing 150 mcg. [1] |
| Health Canada dietary reference intake tables | Pregnancy; breastfeeding | RDA 220 mcg; 290 mcg. Upper level 1,100 mcg. [5] |
| NHS (UK), page reviewed 2020 | Adults | 140 mcg; supplements of 0.5 mg (500 mcg) or less a day unlikely to cause harm. [6] |
| NHS (UK) pregnancy vitamins page, reviewed 2026 | Pregnancy | Recommends folic acid and vitamin D supplements. [7] The page text we read does not mention iodine, so a UK pregnancy-specific iodine figure is not described in the sources we read. |
| EFSA (EU), 2025 overview | Pregnancy; breastfeeding | Tolerable upper intake level 600 mcg a day from all dietary sources. [8] |
| WHO European Region report, 2007 | Pregnant women and young infants | Suggested considering iodine supplementation for these groups where there is insufficient iodized salt. [9] |
The ATA statement is old and described itself as provisional. [2] We did not find a newer ATA figure with a readable text, and we could not read the NIH Office of Dietary Supplements pages, so US figures here come from MedlinePlus, which draws on that office's fact sheet.
What trials and reviews found
Evidence labels used on this page: established role, mixed, insufficient, Proper evidence not found.| Question | What the source found | Strength |
|---|---|---|
| Does severe deficiency harm development? | MotherToBaby says severe iodine deficiency in pregnancy can increase the chance of serious learning problems in the child. [1] | Established role |
| Does mild deficiency harm learning? | MotherToBaby says it is possible, but this has not been clearly proven. [1] | Mixed |
| Do iodine supplements before, during or after pregnancy improve outcomes? | A 2017 Cochrane review found insufficient data on routine supplementation. It found lower postpartum hyperthyroidism (risk ratio 0.32; low-quality evidence) and more digestive intolerance (very low-quality evidence), with no clear differences in most other outcomes. [4] | Insufficient |
| Same question, in mild to moderate deficiency | A 2021 review says Cochrane reviews from 2017 and 2019 found no evidence that supplements improved infant and child cognitive development there, and that there is no scientific evidence to support generalized supplementation in such settings. [10] | Mixed |
| Is more always better? | A 2023 overview of meta-analyses found a U-shaped link between iodine status and maternal and neonatal outcomes. [11] | Mixed |
Trials in severely deficient populations do not transfer to well-nourished ones, and the reverse. Almost all the Cochrane evidence came from mild or moderate deficiency. [4]
Too much iodine
MotherToBaby says very high iodine can cause hyperthyroidism, and the fetus could develop low thyroid hormone or an enlarged thyroid (goiter). [1] It also says it is not recommended to get more than 500 to 1100 mcg a day for long periods while breastfeeding, because too much iodine in breast milk can cause problems with a baby's thyroid. [1] Kelp and seaweed products vary enormously: one analysis found 16 micrograms per gram in nori and over 8,165 micrograms per gram in a processed kelp product. [12] Do not use unlabeled kelp products in pregnancy without advice; see kelp and seaweed supplements.Frequently asked questions
Do I need more iodine when pregnant?
Reference intakes are higher: the US RDA is 220 mcg in pregnancy and 290 mcg while breastfeeding. [3] Ask a midwife or doctor whether your diet and prenatal product cover it.
Is a kelp supplement a good way to get iodine in pregnancy?
The sources we read do not support it as a safe shortcut, because iodine content of seaweed products varies hugely. [12]
Does iodine in pregnancy affect a baby's brain development?
Severe deficiency can; MotherToBaby says mild deficiency may affect learning but this is not clearly proven. [1]
Is it safe to take iodine if I breastfeed?
MotherToBaby reports that the ATA advises continuing a daily supplement during breastfeeding, and that long-term intakes above 500 to 1100 mcg a day are not recommended. [1] Ask your provider and your baby's pediatrician.
Do official bodies agree on the amount?
No. Figures differ by country and year (see the table), and a UK pregnancy vitamins page we read names only folic acid and vitamin D. [7]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Who should ask a clinician first
- Anyone with thyroid disease or thyroid medicine. MotherToBaby advises talking with a provider before taking iodine supplements. [1] NIDDK says many women taking thyroid hormone medicine need a higher dose during pregnancy and should contact their doctor right away if they find out they are pregnant. [13] See iodine and the thyroid.
- Vegan and vegetarian diets. The NHS notes that strict vegans who eat no fish, eggs or dairy may want iodine-fortified foods or a supplement, and to seek professional advice. [6] MotherToBaby notes that vegan and vegetarian diets may supply less iodine. [1] See minerals for vegetarians and vegans.
- Anyone choosing a prenatal product. MotherToBaby says to check the label because some prenatal vitamins do not contain iodine. [1] See prenatal and postnatal vitamins and reading supplement labels.
- Kidney or liver conditions, and before surgery. The sources we read do not address iodine supplements here. Ask your team, and see medication interactions.
For the whole picture see minerals in pregnancy and Pregnancy and breastfeeding safety.
References
- MotherToBaby (Organization of Teratology Information Specialists). Iodine fact sheet (April 2025). Link. Read 2026-10-23.
- Public Health Committee of the American Thyroid Association. Iodine Supplementation for Pregnancy and Lactation: United States and Canada: Recommendations of the American Thyroid Association. Thyroid. 2006;16(10). Link. Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Iodine in diet (review date 21 January 2025). Link. Read 2026-10-23.
- Harding KB et al. Iodine supplementation for women during the preconception, pregnancy and postpartum period. Cochrane Database Syst Rev. 2017. Link. Read 2026-10-23.
- Health Canada. Dietary reference intakes: reference values for elements (tables). Link. Read 2026-10-23.
- NHS (UK). Vitamins and minerals: Iodine (page last reviewed 3 August 2020). Link. Read 2026-10-23.
- NHS (UK). Pregnancy vitamins and supplements (page last reviewed 3 June 2026). Link. Read 2026-10-23.
- European Food Safety Authority. Overview on Tolerable Upper Intake Levels as derived by the SCF and the EFSA NDA Panel, version 11 (August 2025). Link. Read 2026-10-23.
- World Health Organization Regional Office for Europe. Iodine deficiency in Europe: a continuing public health problem (2007). Link. Read 2026-10-23.
- Iodine supplementation: is there a need? Curr Opin Clin Nutr Metab Care. 2021. Link. Read 2026-10-23.
- Croce L et al. Iodine status and supplementation in pregnancy: an overview of the evidence provided by meta-analyses. Rev Endocr Metab Disord. 2023. Link. Read 2026-10-23.
- Teas J et al. Variability of iodine content in common commercially available edible seaweeds. Thyroid. 2004. Link. Read 2026-10-23.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, US). Hypothyroidism (underactive thyroid) (last reviewed March 2021). Link. Read 2026-10-23.