A team at the University of Tasmania’s Menzies Institute for Medical Research found taking an iodine supplement before becoming pregnant was key to maintaining adequate levels of the essential micronutrient during pregnancy.
Laura Laslett knew about the importance of iodine before she became pregnant with her son Samuel three years ago.
“I knew that it [iodine] was important for brain development so we wanted to give our child the best start in life,” she said.
“It was easy to take supplements and we knew it was a good thing to do so that’s something we did as part of planning for a pregnancy.”
But not every woman preparing for pregnancy is aware of the need for iodine.
Iodine is used by the thyroid gland to make hormones needed for a baby’s brain development.
The study tested the iodine levels of 250 pregnant women.
The institute’s Kristen Hynes, who led the study, said the need for folate before and during the first three months of pregnancy was understood but there was little understanding about iodine.
“Our study showed that even though the general population is now considered iodine sufficient — through the iodisation of bread — pregnant women are not going to get enough through that,” she said.
“Only those women who are supplementing prior to pregnancy seem to be able to maintain iodine levels sufficient for brain development of the foetus.”
She said pregnant women need to increase their iodine intake by 50 per cent for optimal brain development of their babies and taking a supplement before conception was important.
“We think that’s all about bringing up the thyroid stores to a level that will be sustained throughout pregnancy,” she said.
“You can increase your levels once pregnancy has started but it may not be enough to put you within the range that’s recommended by the World Health Organisation.”
A previous study showed the children of women whose iodine levels were low during pregnancy had poorer educational outcomes, particularly in literacy.
“Children whose mothers had adequate iodine levels during pregnancy had NAPLAN scores that were above the Tasmanian average, closer to the national average,” Dr Hynes said.
“Those whose mothers had inadequate iodine during pregnancy, their NAPLAN scores were below the Tasmanian average.”
Iodine added to food not enough
Tasmania and much of south-east Australia have soils that are mildly deficient in iodine.
Ten years ago iodised salt was added to bread across Australia to lift iodine levels in the community.
Professor John Burgess from the university’s School of Medicine said the supplementation had worked.
“However, in pregnancy, there’s a substantial increase in iodine requirement and that increase can’t be compensated for by the standard population measure that we use,” he said.
“What we have to do in that sense is to increase iodine through some other means and that, at present, is best done by women taking an iodine supplement.”
The supplement should be taken before pregnancy and combined with a diet of foods rich in iodine like dairy, fortified bread and seafood.
“Taking a 150 microgram supplement prior to conception during pregnancy and during breastfeeding is the best way of ensuring that the level the woman is receiving of iodine is above that 250 microgram total daily level,” he said.
Professor Burgess said the importance of iodine needed to be better understood.
“To get the message out to women who require increased iodine during pregnancy it’s going to be a combined effort between all the players,” he said.
“So it involves medical professionals, it involves other health professionals, it involves a community awareness campaign.”
Fertility dietician Melanie McGrice said iodine was essential for most women in the lead-up to pregnancy, but there were exceptions.
“For some women you don’t want to be having iodine due to things like Graves disease … and hypothyroid conditions, so if you’re unsure it’s worth speaking to a dietician,” she said.
She said it was also important for women check on other nutrients in the lead up to conception such as folic acid, vitamin D, iron and B12.