The effect of iodine deficiency during pregnancy on child development

Abstract

It is well known that severe iodine deficiency during pregnancy may cause impaired brain development in the child, with effects on cognitive and motor function, hearing and speech. Whether mild-to-moderate deficiency also affects neurological development is less well known, but in the past decade a number of observational studies have been conducted to answer this question and these studies are reviewed in this article. The picture is now emerging that even mild-to-moderate iodine deficiency during pregnancy may be associated with subtle impairments in cognition and school performance, although the evidence from randomised controlled trials is still lacking. As global efforts to eradicate iodine deficiency in populations continue, it is more likely that mild-to-moderate, rather than severe, iodine deficiency will be the issue of concern in pregnancy, and therefore further research in regions of mild-to-moderate deficiency is required to strengthen the research base and to inform public-health policy.

Maternal cognitive function during pregnancy in relation to hypo‐ and hyperthyroxinemia

“…17 This suggests that hypothyroxinemia is probably related to the 'massive foetal consumption' of transplacentair transported T4 during gestation. 35,36 In the current study, the number of women with elevated TPO-Ab in women with hypothyroxinemia at different cut-off's (<2.5th, <5th and <10th percentile) remained almost twice as high compared to biochemically euthyroid women ( What might be the clinical relevance of the current findings? 38,39 TPO is a haem enzyme that becomes active only after binding haem.…”

“…Low iron status has been associated with lower TSH, total T4 status and hypothyroxinemia during pregnancy. 35,36 In the current study, the number of women with elevated TPO-Ab in women with hypothyroxinemia at different cut-off's (<2.5th, <5th and <10th percentile) remained almost twice as high compared to biochemically euthyroid women ( Table 2) suggesting that thyroid autoimmunity might be an important cause of hypothyroxinemia, possibly mediated by poor iron status? Unfortunately, iron status and the presence of anaemia were not assessed in the current study.…”

“…36 In addition, food questionnaires assessed at midterm seem to reflect iodine intake but they are not user-friendly (including 225 items). 36 In addition, food questionnaires assessed at midterm seem to reflect iodine intake but they are not user-friendly (including 225 items).…”

“…However, in a recent review, the reliability of a few urine (even 24 hours) iodine assessments (for example each trimester) has been questioned whether it reflects the general iodine intake during pregnancy. 36 In addition, food questionnaires assessed at midterm seem to reflect iodine intake but they are not user-friendly (including 225 items). 36 An alternative could be to assess thyroglobulin as a reflection of long-term iodine intake but TG is susceptible to physiological changes during pregnancy and the presence of Tg-Ab.…”

“…36 In addition, food questionnaires assessed at midterm seem to reflect iodine intake but they are not user-friendly (including 225 items). 36 An alternative could be to assess thyroglobulin as a reflection of long-term iodine intake but TG is susceptible to physiological changes during pregnancy and the presence of Tg-Ab. 37 How to explain the relatively large number of women with hypothyroxinemia during early pregnancy?…”