Associate professor Vicki Clifton from the University of Adelaide's Robinson Institute and the Lyell McEwin Hospital said the study involved almost 200 South Australian women tested for iodine throughout their pregnancy and six months after giving birth.
"Iodine is an essential element which is important for human brain development and thyroid function," Clifton said in a statement. "In 2009, Australian bread producers began a mandatory program of iodine supplementation in bread to help provide a boost to iodine levels in the community. Our study was aimed at determining whether or not that was having a positive impact on iodine levels for pregnant women."
The study, published in the Nutrition Journal, found South Australian women were mildly iodine deficient, Clifton said. "Despite the inclusion of iodized salt in bread, women who were not taking an iodine supplement during pregnancy were still suffering from iodine deficiency."
However, those women who took a supplement in addition to eating bread with iodized salt received healthy levels of iodine, well within World Health Organization guidelines, Clifton said.
Basil Hetzel, an emeritus professor at the University of Adelaide, said Australia continues to be a leader in this field, but "there is still very little public understanding about the dangers of iodine deficiency."
"Iodine deficiency is now recognized by the WHO as the most common preventable cause of brain damage in the world today," Hetzel said.