TempoLife › Features › Reference intakes by nutrient, age and sex › pregnancy

Iodine in pregnancy

Two hundred micrograms a day, up from 150 — a third more, and one of the largest pregnancy increases in the table. The reason is blunt: for the first months, fetal brain development runs entirely on the mother thyroid hormone.

EFSA note on this row: raised by a third for fetal brain development

These are published population reference values, not a diagnosis and not a prescription. A reference intake describes what covers a healthy group; it cannot tell you your own status, and no page can. Pregnancy, chronic illness, medicines and malabsorption all change the picture — take those questions to a doctor, midwife, pharmacist or dietitian.

The timing is the whole argument

The fetal thyroid does not begin producing hormone until partway through pregnancy. Until then, every bit of thyroid hormone reaching the developing brain comes from the mother, and thyroid hormone is built around iodine atoms. Maternal iodine supply in early pregnancy is therefore an input to fetal neurodevelopment in a very direct sense.

The window opens before most women know they are pregnant, which is the same structural problem as with folic acid. It is one reason iodine sufficiency is treated as a matter for women of childbearing age generally, not only for those already pregnant.

Why this is a live issue in the Nordic and Baltic countries

Iodine intake in this region has been a recurring public-health concern, and women of childbearing age have repeatedly been the group closest to the line. The mechanisms are ordinary. Sea salt and rock salt are usually not iodised, so the shift away from iodised table salt removes iodine. Salt-reduction advice, which is correct on its own terms, reduces the vehicle. And dairy, another significant carrier, is often reduced or replaced without a fortified substitute.

None of that is an argument for eating more salt. It is an argument for buying iodised salt when you buy salt, and for knowing where else your iodine comes from.

Where it comes from, and the one to avoid

Iodised salt, milk and dairy, sea fish and eggs are the practical sources in this region. The site food database does not carry iodine values, so this page describes sources rather than ranking them — inventing numbers would be worse than leaving the table out.

Seaweed is the exception that needs a warning rather than a recommendation. Kelp products can carry thousands of micrograms per gram, enough to exceed the 600 microgram adult upper level many times over in a single serving, and both too little and too much iodine disturb the thyroid. Kelp supplements are not a sensible way to cover pregnancy iodine.

This one belongs with your midwife

Thyroid function in pregnancy is monitored clinically where there is reason to, and thyroid disease in pregnancy is managed by specialists. Iodine supplementation in pregnancy is recommended in some countries and handled through diet in others, and the right answer depends on the local food supply as much as on the individual.

Ask at your antenatal appointment. It is a one-sentence question with a locally correct answer, which is more than any reference table can give you.

How this compares with every other group

Ordinary food against the 200 µg figure for pregnancy

The food composition snapshot behind this site does not carry iodine values, so there is no computed table on this page. Inventing numbers would be worse than leaving it out; the sections above describe where it comes from instead.

The whole nutrient, not just this group

The Iodine reference intake page carries the full age and sex table, the upper level, and what the value type means.

Related pages

Sources: EFSA Dietary Reference Values · Regulation (EU) No 1169/2011, Annex XIII · USDA FoodData Central SR Legacy (food composition) · EFSA scientific opinion on dietary reference values for iodine (2014) · World Health Organization guidance on iodine deficiency and salt iodisation · checked 2026-09-06

Frequently asked questions