Iodine in pregnancy: How much do you need and why?

Iodine is needed for the development of the brain and nervous system.
Written by
Molly McLaughlin
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Last updated on
June 4, 2024
min read
Why Is Iodine So Important In Pregnancy? | Kin Fertility
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As an expectant mum, there is a whole bunch of things to keep an eye on when it comes to your health.

Iodine status is definitely one of the important ones, as it is an essential part of a healthy diet for everyone, but especially for those who are trying for a baby, pregnant or breastfeeding.

This is because iodine is needed for the healthy development of the brain and nervous system, from foetuses before birth right up to school-aged children. The average person needs around 150 micrograms of iodine per day, which can usually be achieved through diet alone.

During pregnancy and breastfeeding, however, your iodine intake should be much higher. In these cases, an iodine supplement is recommended to help maintain a balanced diet for mums and bubs.

If you're pregnant (or hoping to be), this guide will cover when, why and how to take an iodine supplement for yourself and your baby.

What is iodine?

Like copper and zinc, iodine is a trace element that must be present in small amounts in the body for normal functioning.

In its natural form, iodine is a shiny, non-metallic solid that can be dark grey or purple. Because of the small quantities needed by humans, iodine is virtually undetectable in foods and supplements.

Iodine can be consumed in seaweed, cooked seafood, eggs and dairy products. Since the 1920s, it has also been added to salt as a safe and cost-effective way to increase iodine levels across the world.

According to UNICEF, being iodine deficient remains the second most common form of micronutrient deficiency among adolescents (after iron).

Children who don't get enough iodine can struggle to learn and develop at the same pace as their peers, alongside a wide range of other effects on intellectual development and cognitive outcomes that begin to develop during pregnancy.

Why is iodine important during pregnancy?

For pregnant and breastfeeding people, iodine status plays a huge role in growing a healthy baby. Iodine in pregnancy has been shown to affect the coordination, alertness and normal development of the senses in infants and young children through the brain and nervous system.

Without enough iodine, foetal health issues as serious as brain damage and mental developmental problems can occur. In fact, iodine deficiency during pregnancy is cited as the single largest cause of avoidable intellectual impairment worldwide.

Iodine is an essential and under-appreciated part of how your baby develops.

Why do you need more iodine during pregnancy?

These far-reaching consequences of iodine deficiency disorders can be traced back to iodine's effect on the mother's thyroid during pregnancy. The thyroid is the organ responsible for absorbing, storing and releasing this essential micronutrient through a process called thyroid hormone synthesis.

As the baby's thyroid is still developing, the thyroid hormones travel through the placenta to the baby's brain during pregnancy.

Severe iodine deficiency in pregnant women results in insufficient thyroid hormone production, which then impairs the normal development of the brain and nervous system of the baby in utero. Increasing iodine has even been found to reduce rates of infant mortality.

Fortunately, there are plenty of dietary supplements available designed as alternative sources of iodine for pregnant women.

How much iodine do pregnant people need?

The average person needs 150 micrograms of iodine per day, which can usually be achieved by consuming iodised salt as part of a healthy diet. Certain factors, such as eating vegan, make this more difficult, so pregnant and breastfeeding women may need to consider making adjustments to their diet.

During pregnancy, the recommended iodine intake jumps to 220 micrograms of iodine, and then to 270 micrograms of iodine while breastfeeding.

It is recommended that pregnant and breastfeeding people use iodine supplementation to ensure enough is available to be passed on to the baby. While a microgram is a tiny amount (only one millionth of a gram!), iodine still needs to be consumed regularly because the body can only store limited quantities.

Of course, if you have any concerns about the specific iodine intake that is right for you during pregnancy, make sure to consult a doctor. Your health professionals will be able to measure your urinary iodine concentration to ensure you're on the right track, as well as check for thyroid dysfunction during pregnancy and breastfeeding.

Are pregnant and breastfeeding people in Australia getting enough iodine?

Although levels of iodine deficiency rapidly fell after the introduction of iodised salt in Australia, they have recently begun to rise again. This worrying trend is due to the fact that, in the past, a significant proportion of our iodine intake came from contamination of dairy products.

Up until the 1990s, so-called 'positive contamination' occurred because iodine was used to clean milking equipment, which led to a small amount being passed on to the consumer in the milk.

In recent years, chlorine has been more commonly used to clean milking equipment and this valuable source of iodine has been lost. A study in 2010 found that, overall, Australian children and pregnant people have a mild iodine deficiency.

In addition, a considerable proportion of the pregnant population have moderate to severe iodine deficiency, raising serious concerns about the flow-on health effects of too little iodine in our diets.

In 2009, mandatory fortification of bread with folic acid and iodine was introduced by the Australian and New Zealand governments as a national health measure, which has made some progress in improving levels of these trace elements. (Folic acid can help prevent birth defects such as spina bifida.)

But for pregnant and breastfeeding people, much more needs to be done to raise awareness about the need for iodine.

How to get enough iodine when pregnant?

No matter how much iodine you consume in food, health guidelines recommend an iodine supplement for all pregnant and breastfeeding women.

Seaweed and cooked seafood are good natural sources, but relying purely on dietary intake for this essential nutrient makes it hard to measure if you're getting enough iodine during pregnancy.

When should you start taking iodine supplements?

The effects of iodine deficiency on a baby's brain and nervous system cannot be reversed later in life, so it is essential that pregnant and breastfeeding women maintain sufficient iodine levels from the get-go.

Even when trying to conceive, iodine deficient women may find it harder to fall pregnant and experience an increased risk of miscarriages.

You can start taking iodine supplements as soon as you decide to try for a baby, or even when you start taking folic acid (which is recommended from 12 weeks before conception).

Starting supplements early will avoid inadequate iodine intake during the first trimester and promote healthy brain development and physical development. You should continue taking iodine throughout the pregnancy and breastfeeding process, as it can be passed on to your baby through breast milk.

When should you stop taking iodine supplements?

Your iodine requirements drop significantly after you stop breastfeeding, as you are no longer needing to generate enough thyroid hormones for two bodies. Most doctors only recommend dietary supplements during pregnancy and breastfeeding.

After that, dietary sources of this essential mineral will likely be enough and you can stop taking your iodine supplement.

Which trimester is iodine most important?

While iodine is necessary throughout a baby's development, it is most important for pregnant women during the first trimester when the thyroid gland of the foetus is still developing.

To help both mum and bub thrive, health professionals suggest combining dietary sources of iodine with supplements across all stages of pregnancy.

What foods contain high levels of iodine?

So once you're taking prenatal vitamins, what else can you do to maintain levels of iodine in pregnancy? Dietary sources should be used in conjunction with supplements to make sure that there is enough iodine in your system.

Buying iodised salt is the easiest way to up your intake. However, it's best not to increase overall salt consumption, as it can have adverse effects on your heart and blood pressure.

If you need more iodine, check the nutritional information of your bread to make sure it is the best option. Eggs, fish and seaweed should also be integrated into your diet in moderation.

While pregnant, some seafood is off-the-menu due to the risk of mercury poisoning, such as shark, swordfish and king mackerel. As the top of the food chain, these large, predatory fish have the highest accumulation of mercury.

Instead, opt for smaller fish like salmon, herring, anchovies and sardines which still offer all the nutritional same benefits as their larger counterparts. Cooked fish and seafood is also recommended to prevent any risk of viruses or bacteria affecting the baby.

So, whether you're already pregnant or just thinking about it, an iodine supplement should be a key part of your daily routine.

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