Iodine in Pregnancy and Breastfeeding: How Much You Need in Australia

If you've looked up iodine in pregnancy in Australia, you've probably met three different numbers. The recommended dietary intake (RDI) is 220 mcg a day in pregnancy and 270 mcg while breastfeeding. The official advice is to take a 150 mcg supplement. And the label on your prenatal may say something else again.

In clinic, the most common iodine question I got wasn't "do I need it?" It was "am I taking too much?"

As a naturopath and a mum of four, I can tell you these numbers do fit together. You just need to know what each one is measuring.

Quick answer: in Australia, the NHMRC recommends a 150 mcg iodine supplement every day from the time you're planning pregnancy until you stop breastfeeding, on top of a varied diet. Your total intake from food and supplements should land around 220 mcg a day in pregnancy and 270 mcg while breastfeeding. Get your iodine from one reliable source, and talk to your doctor first if you have a thyroid condition.

Below is the detail behind each of those numbers, who tends to fall short, how to avoid doubling up, and what to check on your label.

Why iodine matters in pregnancy and breastfeeding

Your thyroid uses iodine to make thyroid hormones. Those hormones help regulate metabolism, growth and development, which is why your iodine needs rise when you're growing and then feeding a baby.

Your body can't make iodine and can't store much of it, so it has to come in regularly through food and, in these seasons, a supplement (FSANZ).

In pregnancy

Pregnancy asks more of your thyroid. Thyroid hormone production increases by around 50%, and your kidneys clear iodine faster than usual, by an estimated 30–50% (American Thyroid Association). Some of your iodine also crosses the placenta to your baby.

In early pregnancy your baby relies on your thyroid hormones. Later, its own thyroid starts working, using iodine that still comes entirely from you.

The NHMRC describes iodine as needed for the thyroid to produce hormones that support normal development of the brain and nervous system before birth, and in babies and young children (NHMRC). That is the reason Australian guidance treats iodine as a nutrient to plan for, rather than one to leave to chance.

While breastfeeding

Once your baby is born, breast milk becomes their only source of iodine. The NHMRC notes that breastfed babies are completely dependent on milk for iodine, needing around 90–100 mcg a day to build their own thyroid hormone stores (NHMRC public statement).

How much iodine is in your milk depends on how much you take in. That's why the breastfeeding RDI (270 mcg) is higher than the pregnancy RDI (220 mcg). Breastfeeding is the stage of highest iodine need.

How much iodine do you need in pregnancy in Australia?

The NHMRC recommends that all women who are planning a pregnancy, pregnant or breastfeeding take a 150 mcg iodine supplement every day, and that women with a pre-existing thyroid condition speak with their doctor first (NHMRC).

Sources: NRVs for Australia and New Zealand – iodine; NHMRC.

One update to know about. The NHMRC is reviewing the iodine NRVs. The RDIs stay the same, but the draft proposes lowering the adult Upper Level, including in pregnancy and breastfeeding, from 1,100 mcg to 600 mcg a day (NHMRC consultation). Final values are expected to be published in 2026. I'd treat 600 mcg as the more useful ceiling to keep in mind.

Why is the supplement 150 mcg when the RDI is 220 or 270 mcg?

This is the part that confuses almost everyone, and it comes down to what each number measures.

The RDI is your total daily intake from every source: food, drinks, iodised salt and supplements combined. It's set high enough to cover nearly everyone, around 97–98% of healthy people (NHMRC).

The 150 mcg supplement is a top-up, designed to sit on top of what your diet already provides. It isn't meant to supply the whole RDI by itself.

Here's how that plays out on three different days, using FSANZ food figures (FSANZ). All totals are approximate.

Three things stand out.

• On a typical day, a 150 mcg supplement brings you into the pregnancy range. That's the gap it was designed to close.
• On a low-iodine day, 150 mcg leaves you short of both the pregnancy (220 mcg) and breastfeeding (270 mcg) RDIs. What you eat changes how much your supplement needs to do.
• Even a seafood day stays under the proposed 600 mcg Upper Level with one supplement. Add a separate 150 mcg iodine tablet on top of a 270 mcg prenatal and that day reaches about 670 mcg. The Upper Level is about your usual daily intake, so an occasional high day isn't a concern. Stacking products makes it your usual.

When to start, and how long to take it

• Planning: start when you begin trying, ideally a few months beforehand. If your pregnancy wasn't planned, start as soon as you find out (NSW Health).
• Pregnancy: every day, all the way through.
• Breastfeeding: for as long as you breastfeed, whether that's six weeks or two years.

Why Australian women fall short on iodine in pregnancy

Australian soils are low in iodine, so most of what we grow carries very little. For decades, dairy made up some of the difference: farms used iodine-based sanitisers on milking equipment, and some of it ended up in the milk. As the industry switched to chlorine-based sanitisers, the iodine content of milk fell (MJA, Li et al. 2006).

The Australian National Iodine Nutrition Study (2003–04) then found that mainland schoolchildren were mildly iodine deficient as a group, particularly in the south-eastern states (MJA, Li et al.).

In response, iodised salt became mandatory in bread from October 2009 (FSANZ monitoring report). By 2011–12, the population overall was iodine sufficient. Women of childbearing age were still lagging, though: nearly two-thirds had urinary iodine below the level recommended for pregnancy and breastfeeding (ABS Australian Health Survey).

That's why the supplement recommendation still stands. Fortified bread lifted the floor for the population. The NHMRC is clear it isn't enough to cover the extra needs of pregnancy and breastfeeding.

Who is more likely to fall short

• You don't eat standard bread. Bread labelled organic is exempt from mandatory fortification. Two slices of organic bread provide about 2 mcg, compared with about 28 mcg from standard bread (FSANZ).
• You eat gluten-free. Most ready-made, yeasted gluten-free loaves are made with iodised salt, but gluten-free bread mixes for home baking are not (Coeliac Australia). Check the ingredients list for "iodised salt".
• You bake your own, eat mostly wraps or flatbreads, or are low-carb. Home bread mixes, salt-free bread and unleavened breads aren't fortified, and low-carb eating removes the main fortified food altogether.
• You avoid dairy. Milk is one of the bigger everyday sources. Plant milks don't carry iodine unless the label says it has been added.
• You eat a plant-based diet, which often removes dairy, eggs and seafood at once.
• You don't use iodised salt. Sea salt, pink salt and most gourmet salt flakes are not iodised unless the pack says so. Most of the salt in packaged foods isn't iodised either.

If two or more of these describe you, your days probably look more like the low-iodine row in the table above than the typical one. That makes a consistent daily supplement the part of your intake you can actually count on.

Can you get too much iodine?

Yes. Most iodine articles only talk about deficiency, but excess can also disrupt normal thyroid function, particularly in women who already have a thyroid condition (NHMRC).

The Upper Level is the highest daily intake, from all sources combined, that is likely to cause no adverse effects for almost everyone. It's currently 1,100 mcg a day. The NHMRC has proposed lowering it to 600 mcg after newer research showed some people develop mild thyroid changes at lower intakes than previously recognised. A normal diet plus one well-dosed prenatal sits comfortably below either figure. Where intake creeps up is in the two situations below.

Kelp and seaweed supplements

FSANZ advises against kelp and seaweed supplements in pregnancy because their iodine content varies (FSANZ). One study measured prenatal vitamins using kelp as the iodine source and found anywhere from 33 to 610 mcg per daily dose, often well off the label (Pearce et al., via Healio). Potassium iodide, by contrast, is a measured ingredient with a predictable dose.

The same goes for very seaweed-heavy eating. A sushi roll is fine. Seaweed products themselves can contain hundreds of micrograms, sometimes several milligrams, of iodine (FSANZ).

Stacking products

This is the most common way women overshoot, usually without realising. A typical stack looks like this:

• a prenatal that already contains iodine, plus
• a separate iodine tablet "because the midwife mentioned iodine", plus
• a kelp or "thyroid support" product picked up along the way.

Each one seems reasonable on its own. Together, with diet on top, total intake can drift towards the Upper Level for no added benefit.

If you have a thyroid condition

If you have a pre-existing thyroid condition, the NHMRC advises speaking with your doctor before taking an iodine supplement. That includes a prenatal containing iodine. Your doctor or endocrinologist can tell you what's right alongside any thyroid monitoring or medication you have.

Should you test your iodine levels?

Not as a way to choose your dose. Urinary iodine, the measure used in national surveys, mostly reflects what you ate in the last day or so. It's designed to assess populations, and a single result can't tell you whether your usual intake is adequate (ABS).

Thyroid function tests are a different thing. They show how your thyroid is working rather than how much iodine you're getting, and your GP or obstetrician will order them when there's a clinical reason to.

The more useful check is one you can do at home: add up your usual food and read your label.

The practical rule: one well-dosed iodine source, a known daily total, no kelp.

How to check your prenatal for iodine

Turn the bottle over and look for three things.

1. Iodine in mcg per daily dose. Many labels list per capsule or tablet. If the daily dose is two capsules, double it.
2. The form. Potassium iodide (or potassium iodate) is a measured, standardised ingredient. Kelp, seaweed or "sea vegetable" listed as the iodine source is not.
3. Whether there's any iodine at all. Some prenatals on the Australian market contain 150 mcg, some contain more, and some, particularly imported formulas made for other countries, contain little or none.

If your prenatal provides 150 mcg or more of iodine per daily dose from potassium iodide, you generally don't need a separate iodine supplement. Adding one is how most women end up stacking. 

Where EverNatal sits

When I formulated EverNatal, I set the iodine at 270 mcg per two-capsule daily dose, as potassium iodide, which is the same figure as the breastfeeding RDI. 

I chose that number deliberately. EverNatal is one formula for preconception, pregnancy and breastfeeding, and breastfeeding is the season with the highest iodine need. It's also when diet tends to slip and iodine-rich foods are easy to miss. Many of the women I formulate for eat organic or homemade bread, avoid dairy, or use sea salt. For them, food may be contributing very little. You can see it in the low-iodine row of the table above: with a 150 mcg supplement, that day lands around 175 mcg, short of both RDIs. I wanted the prenatal itself to cover the full breastfeeding RDI. 

It's above the NHMRC's 150 mcg baseline, so you should know where that leaves your total. For most women eating a typical Australian diet, EverNatal plus food sits well under the Upper Level, including the lower 600 mcg figure the NHMRC has proposed.

What it does mean in practice: if you take EverNatal, don't add a separate iodine supplement or kelp. It's designed to be your one source. As with any iodine-containing prenatal, talk to your doctor first if you have a pre-existing thyroid condition.

EverNatal's iodine is included to help support healthy thyroid hormone production and thyroid gland function in pregnancy.

Always read the label and follow the directions for use. Supplements should not replace a balanced diet.

Keep taking it while breastfeeding

This is the stage most women drop their prenatal. The baby's here, the routine has changed, and the bottle runs out and doesn't get replaced. It's also the stage of highest iodine need, and your baby's only source is your milk. Keep taking your prenatal for as long as you're breastfeeding.

Food sources of iodine

Seafood, dairy, eggs and fortified bread are the main dietary sources in Australia. The amounts below are approximate, because iodine content varies with where food is grown and how it's made.

Source: FSANZ, Iodine in food and iodine requirements.

Seafood is the richest everyday source, and fish brings other nutrients worth having in pregnancy. Some larger fish are higher in mercury, so follow the FSANZ advice on mercury in fish for which types to limit.

Even a well-planned diet is unlikely to reach 220–270 mcg every day for most women. Most Australian foods contain only small amounts of iodine, which is exactly why the NHMRC recommends a supplement on top (NHMRC public statement).

Frequently asked questions

How much iodine do I need when pregnant in Australia?

The RDI in pregnancy is 220 mcg a day from all sources combined. The NHMRC recommends a daily 150 mcg iodine supplement from the time you're planning pregnancy, on top of a varied diet. If you have a pre-existing thyroid condition, speak with your doctor before taking one.

Why is the iodine supplement 150 mcg when the RDI is 220 mcg?

The RDI is your total intake from food, iodised salt and supplements together. The 150 mcg supplement is designed to close the gap on top of what a typical Australian diet already provides, roughly 100 mcg for many women. It isn't meant to supply the full RDI on its own.

Do I need to keep taking iodine while breastfeeding?

Yes. Breastfed babies rely entirely on breast milk for iodine, and the iodine in your milk reflects your intake. The breastfeeding RDI (270 mcg) is the highest of any life stage, so the NHMRC recommends continuing a supplement for as long as you breastfeed.

Does my prenatal already have enough iodine?

Check the label for iodine in mcg per daily dose, not per capsule, and look for potassium iodide as the source. If it provides 150 mcg or more, you generally don't need a separate iodine supplement. Some prenatals, particularly imported ones, contain little or none.

Can I take iodine if I have a thyroid condition?

The NHMRC advises women with a pre-existing thyroid condition to speak with their doctor before taking an iodine supplement, including a prenatal that contains iodine. Your doctor can advise on the right approach alongside any monitoring or medication. A urine iodine test isn't a reliable way to check your own levels, as it reflects recent intake and is designed for population studies (ABS).

Is kelp a good source of iodine in pregnancy?

No. FSANZ advises against kelp and seaweed supplements in pregnancy because the amount of iodine they contain varies widely and can be very high. Choose a supplement with iodine as potassium iodide, so you know your actual daily dose.

The short version

• Take an iodine supplement every day from planning, through pregnancy, and for as long as you breastfeed. The NHMRC baseline is 150 mcg.
• Get it from one reliable source, ideally your prenatal, with iodine as potassium iodide.
• Check your label per daily dose, add up your total, and don't stack a separate iodine product or kelp on top.
• Keep eating a varied diet with fortified bread, dairy, eggs and seafood. The supplement tops up your diet, it doesn't replace it.
• If you have a thyroid condition, talk to your GP, obstetrician or midwife before you start.

If you'd like a prenatal that covers iodine alongside choline and methylfolate in one formula, you can read more about EverNatal. Not sure what you need for your season? Our quiz takes a couple of minutes.

Always read the label and follow the directions for use. Supplements should not replace a balanced diet.

References

1. NHMRC. Iodine supplementation for pregnant and breastfeeding women (public statement, 2010).
2. NHMRC. Nutrient Reference Values for Australia and New Zealand: Iodine.
3. NHMRC. Public consultation on draft iodine NRVs and FAQs.
4. FSANZ. Iodine in food and iodine requirements.
5. FSANZ. Iodine and pregnancy.
6. FSANZ. Monitoring the Australian population's intake of dietary iodine before and after mandatory fortification.
7. ABS. Australian Health Survey: Biomedical Results for Nutrients, iodine feature, 2011–12.
8. Li M, Eastman CJ, et al. Are Australian children iodine deficient? Results of the Australian National Iodine Nutrition Study. Med J Aust 2006;184(4):165–9.
9. Li M, Waite KV, Ma G, Eastman CJ. Declining iodine content of milk and re-emergence of iodine deficiency in Australia. Med J Aust 2006.
10. NSW Health. Iodine supplements factsheet.
11. Coeliac Australia. Iodine fact sheet (2026).
12. American Thyroid Association. Iodine needs in the pregnant and postpartum woman.
13. Pearce EN et al. Iodine content of prenatal multivitamins in the United States, reported in Endocrine Today (2009).