A low iodine intake among pregnant women may be associated with poor language development, reduced fine motor skills and behavioral problems when the child is three years old.
These are findings from the Norwegian Mother and Child Cohort Study (MoBa).
Iodine is a nutrient needed to produce thyroid hormones, which in turn are essential for brain development.
“We see an association between low iodine intake and language, fine motor skills and behavior, but not with gross motor skills or the age when the child starts walking,” says Anne Lise Brantsæter.
Brantsæter is a researcher at the Norwegian Institute of Public Health.
She is leading a project where researchers study how iodine intake from food or from supplement use by pregnant women is associated with various neurodevelopmental outcomes in children in MoBa.
Many pregnant women have a low iodine intake
Iodine intake was calculated based on a detailed food-frequency questionnaire answered mid-pregnancy by MoBa participants.
More than half (63 per cent) of pregnant women in MoBa had a lower iodine intake than recommended (175 μg / day is recommended for pregnant women according to the Nordic Nutrition Recommendations) and many had a significantly lower iodine intake.
17 per cent had an intake below half of the recommended values.
A high prevalence of low iodine intake among pregnant women and women of childbearing age in Norway has been confirmed by other studies. Iodine deficiency is also very common worldwide and the results of this research are relevant to other countries.
Iodine supplements do not seem to protect
“In this study we also looked at whether iodine from supplements is protective, but the results do not suggest this. One possible explanation may be that starting to take an iodine supplement when pregnant may be too late to have beneficial effects,” explains Brantsæter.
Small, yet concerning effects
Although the effects on each child may be minor, with such a high proportion of Norwegian pregnant women having a low iodine intake, the results are of concern.
“If the assumptions for our calculations are correct and the associations we see actually reflect causal relationships, then mild to moderate iodine deficiency is significant for the occurrence of behavioral problems and language delays among Norwegian three-year-olds,” says Brantsæter.
“In this kind of study, we can never be entirely sure that the relationships we see really represent causal relationships.”
“Nevertheless, there is much to indicate that these findings should be taken seriously. Our findings are supported by those of other studies, but more research is necessary,” she adds.