Iodine and trying to conceive – why the trace element matters so much

Germany is an iodine-deficient region, and this is particularly relevant for women trying to conceive and during pregnancy. Iodine is an essential trace element that the body cannot produce itself. Without enough iodine, the thyroid cannot produce thyroid hormones. These are indispensable for a healthy pregnancy.

Why is iodine important when trying to conceive?

Thyroid hormones (T3 and T4) are made from iodine. They control metabolism, cell division and the development of the nervous system. When trying to conceive and in early pregnancy they are particularly important: until the 12th–14th week of pregnancy the foetus cannot yet produce its own thyroid hormones and depends entirely on the supply from the mother.

Iodine deficiency in the mother can lead to delayed brain development in the child. Studies show that children of mothers with iodine deficiency can have a measurably lower IQ. In addition, growth delays, hearing defects and motor developmental disorders are documented as consequences of pronounced iodine deficiency (gesund-ins-leben.de, Thieme 2025).

What is the supply situation in Germany?

According to the DEGS study (Robert Koch-Institut), the median iodine intake of women of reproductive age was around 125 µg per day, well below the recommended 200 µg for adults and 230 µg for pregnant women (D-A-CH reference values, gesund-ins-leben.de).

An estimated 35–45% of all women of reproductive age take in too little iodine. Iodised salt alone is generally not enough to cover the requirement.

How much iodine is recommended?

Recommendation (D-A-CH):

• Women outside pregnancy: 200 µg/day
• Pregnancy: 230 µg/day
• Breastfeeding: 260 µg/day

Because the requirement often cannot be covered by diet alone, the German Federal Institute for Risk Assessment (BfR) and the initiative "Gesund ins Leben" recommend supplementing with 100–150 µg iodide per day from the time you start trying to conceive – that is, before pregnancy (BfR 2022, Thieme 2025).

Iodine and Hashimoto's – no contradiction

A common uncertainty: may I take iodine if I have Hashimoto's?

In most cases the answer is yes. For women with Hashimoto's thyroiditis, an iodine intake in amounts that match requirements – through iodised salt, iodine-containing foods and a supplement of 100–150 µg/day – is, on current knowledge, generally unproblematic (gesund-ins-leben.de).

An exception is Graves' disease (an overactive thyroid caused by an autoimmune disease). Here iodine preparations should be avoided. The same applies to known autonomous adenomas in a goitre with latent hyperthyroidism (jodmangel.de).

A raised TSH value and Hashimoto's thyroiditis are not a contraindication for iodine – quite the opposite.

What should you look out for when supplementing?

• Choose a preparation with 100–150 µg iodide, not a high-dose algae or kelp product (iodine content often uncontrollably high, BfR warning)
• Many pregnancy vitamins already contain iodine. Check the iodine content on the pack to avoid double supplementation
• Ideally, start taking it as soon as you are trying to conceive, not only once the pregnancy has been confirmed
• If you have a thyroid condition: talk to your doctor before starting supplementation

Conclusion

Iodine is one of the few micronutrients for which the recommendation to supplement begins before pregnancy – the same applies to folic acid. Anyone who lives in Germany, is trying to conceive and does not have a thyroid condition with overactivity should supplement 100–150 µg iodide daily. The evidence for this is clear, and safety at these amounts is established.

Dr. med. Wibke Wilkening is managing physician at Praxis für Fertilität – Kinderwunsch- und EndometrioseZentrum Berlin.

Sources

• BfR (2022): Jod, Folat/Folsäure und Schwangerschaft. Bundesinstitut für Risikobewertung
• Gesund ins Leben / aid infodienst: Supplement Jod – Handlungsempfehlungen. gesund-ins-leben.de
• Thieme Connect (2025): Jodsupplementierung vor, während und nach der Schwangerschaft. DOI: 10.1055/a-2739-3580
• D-A-CH-Referenzwerte für die Nährstoffzufuhr: Deutsche Gesellschaft für Ernährung (DGE)
• DEGS-Studie: Jodzufuhr bei Frauen im reproduktionsfähigen Alter, Robert Koch-Institut