Iodine supplements in pregnancy

Iodine supplements in pregnancy

If you’re pregnant, thinking about falling pregnant or have recently had a baby you probably know about taking folic acid during pregnancy to reduce the risk of neural tube defects (spina bifida and related problems) for your baby. But, did you also know it’s important to take iodine during pregnancy?

What is iodine and why is it important?

Iodine is a naturally occurring mineral that is essential for healthy brain and nervous system development.

We consume iodine in the food that we eat—mostly in seafood, bread and bread products and milk and dairy products.

Iodine deficiency can lead to problems with brain and nervous system development and iodine deficiency is the commonest preventable cause of intellectual impairment worldwide!

Babies can’t produce their own iodine, so they rely on mum’s iodine intake (and thyroxine production) to optimise their brain and nervous system development.

Inadequate iodine intake for mum leads to insufficient thyroxine hormone to the baby, which can impair development of the baby’s brain and nervous system. This, in turn, can increase infant mortality and can seriously impact on mental capacity later in life. Unfortunately these changes are generally irreversible.

Is the Australian population iodine deficient?

Before the 1950s iodine deficiency was not uncommon in Australia. When iodised salt and the use of iodine-based cleaning products in the dairy industry were bought in this problem largely went away. 

But, the use of these cleaning products was phased out in the 1990s and household consumption of salt has fallen too. Fast forward to today and on the whole the Australian population is now mildly iodine deficient.

It is estimated that pregnant women in Australia generally only manage to consume 50 per cent of the recommended daily intake from dietary sources.

So where do we get iodine?

Iodine is found in varying amounts in the food we eat—mostly in seafood, bread and milk and also in some vegetables. The iodine content can vary depending on the season, how and where it is grown and also the processing involved.

All bread and bread products (bread rolls, buns, etc.) sold in Australia, with the exception of organic bread and bread products, now contain iodine.

How much iodine do we need?

The recommended daily intake (RDI) for iodine in adults who aren’t pregnant or breastfeeding is around 150mcg per day. Most people can meet this (or nearly meet this) with their diet alone and don’t need to take a specific iodine supplement as well.

However during pregnancy and breastfeeding much more iodine is needed to meet the needs of both mum and the growing baby. For this reason, the RDI for pregnant and breastfeeding women is much higher at around 250mcg daily, and it’s generally not feasible to meet this through dietary intake alone.

So, women who are thinking about falling pregnant, pregnant or breastfeeding are recommended to take an iodine supplement at a dose of 150mcg daily. This is as well as the iodine in our diet. 

Can I take too much iodine?

Basically, no. But there is no point taking more than the RDI. We can only store small amounts of iodine in our bodies and any excess iodine is excreted. So, there is no benefit to taking more than the recommended daily intake—you will just pee it out!

However, women with pre-existing thyroid conditions are advised to discuss their iodine requirements with their doctor.

What else do I need to be careful of?

It’s best to avoid other sources of iodine, such as kelp and seaweed extract. The iodine content in these may vary so it’s hard to know whether you are actually taking the right amount. These products may also be contaminated with heavy metals such as mercury, which may be harmful to you or your baby.

When do I start taking iodine and which supplement should I take?

Ideally you should start taking iodine before you fall pregnant, and if not, start as soon as you find out you’re expecting. If you are currently breastfeeding you may want to think about starting it now.

There are lots of supplements on the market that contain iodine. Check whether the supplements you are taking (or thinking about taking) contain the correct dose for pregnancy and breastfeeding (150mcg). Ideally look for a supplement that is designed for pregnancy and/or breastfeeding, and even then, check that the dosage is correct. If you have questions or concerns ask your doctor or midwife.


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For urgent assessment at any stage of your pregnancy, please present to your nearest emergency centre or Mater Mothers’ 24/7 Pregnancy Assessment Centre in South Brisbane.

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