Iodine in pregnancy: how much, and where it comes from

Why iodine matters in pregnancy

Iodine contributes to normal thyroid function and to normal cognitive function, and the demand rises in pregnancy. In the terms the UK allows, iodine contributes to normal cognitive function and to the normal production of thyroid hormones. Most people here get what they need without thinking about it, from dairy and white fish, which are the main UK sources.

Who is most likely to fall short

The adult reference intake in the UK is 140 micrograms a day, and needs are higher in pregnancy. The people most likely to be low are those who avoid the main sources: if you do not eat dairy or fish, for example on a vegan or dairy-free diet, iodine is one to plan for. Looking at what you eat in a typical week usually makes it clear. Little or no dairy and no white fish is the pattern to watch.

The care point: measured versus unmeasured

Seaweed and kelp are naturally rich in iodine, which is why they turn up as iodine sources. Kelp itself is fine; the concern is kelp whose iodine content you cannot measure. A raw kelp or seaweed supplement can carry a high and unpredictable amount, so it is easy to get far more than you intend, and too much iodine is a problem in its own right. What you want in pregnancy is a known, consistent dose that has been standardised and declared on the label, instead of the guesswork of a raw kelp tablet. Dietitians make the same point: be careful with unmeasured kelp.

A declared amount in a prenatal

A prenatal that states its iodine on the label gives you that known amount. Ours provides 290 micrograms of iodine, standardised from wild, hand-harvested kelp, which sits above the higher needs of pregnancy and comfortably below the safe upper level. Because it is declared and consistent, you know how much you are taking. As with anything in pregnancy, run your plan past your midwife, especially if you have a thyroid condition.