Iodine Supplementation in Pregnancy and the Dilemma of Ambiguous Recommendations

Abstract

Iodine requirements are increased during pregnancy, predominantly caused by an increase in renal iodide clearance and in the use of iodine for thyroid hormone production. Because iodine deficiency (ID) in pregnancy may be associated with neurodevelopmental deficits in the offspring, a pertinent question is at what level of iodine intake pregnant women should be advised to take iodine-containing supplements. The consensus reached by the WHO/UNICEF/ICCIDD in 2007 was that pregnant women should not be recommended to take iodine-containing supplements if the population in general had been iodine sufficient for at least 2 years. However, guidance on this differs between scientific societies. This review discusses iodine supplementation in pregnancy. Based on current evidence, the recommendations given by WHO/UNICEF/ICCIDD in 2007 provide a valid guidance on the use of iodine supplements in pregnant women. Women living in a population with a median urinary iodine concentration (UIC) at or above 100 µg/l are not in need of iodine supplementation in pregnancy. On the other hand, if the population median UIC is below 100 µg/l, pregnant women should take iodine-containing supplements until the population in general has been iodine sufficient for at least 2 years by way of universal salt iodization.

Low intake of iodized salt and iodine containing supplements among pregnant women with apparently insufficient iodine status - time to change policy?

“…Importantly, it is currently unclear whether fortification alone can provide adequate iodine intake during pregnancy and lactation [39,42,43], and the range of appropriate iodine levels is narrow. Moreover, if a country moves ahead with a Universal Salt Iodization Program, then its ICS recommendations for PW must be carefully calibrated so that women of child bearing age and PW get the appropriate amount of iodine neither too little nor too much [39,[43][44][45][46][47][48]. Intake of both IS and ICS, together with other iodine rich food sources, may potentially lead to excessive iodine intake [16,30,39,49] 1 .…”

Assessing Iodine Status in Frontline Healthcare

“…Maternal thyroid function and iodine levels have been shown to markedly affect foetal neurodevelopment, learning skills and IQ of offspring, and placental growth which in turn affects foetal growth. Iodine requirements are increased in pregnancy and are unlikely to be met in any country with mild deficiency [11]. Some countries such as Australia and New Zealand have issued supplementation guidelines for all pregnant women at 150 µg per day [12].…”

“…Some countries such as Australia and New Zealand have issued supplementation guidelines for all pregnant women at 150 µg per day [12]. However, there is much debate over the risks of supplementation in populations where a proportion of individuals could be replete [11].…”

Development of cereal bars with adequate nutritional profile for each trimester of pregnancy– An exploratory study

“…The recommended daily dose is 350mg 3 . Iodine: Iodine deficiency in pregnancy may be associated with deficits in fetal neurological development 21 . In Portugal, guidelines recommend supplementation with potassium iodide (150-200 μg/day) 10 , accompanied by dietary sources of iodine for preconception, pregnant, and women who are breastfeeding exclusively 22 .…”

“…A dose diária recomendada é de 350mg 3 . Iodo: A deficiência de iodo na gravidez pode estar associada a défices de desenvolvimento neurológico no feto 21 . Em Portugal as diretrizes recomendam uma suplementação com iodeto de potássio (150-200 μg/dia) 10 acompanhada de uma alimentação que inclua fontes de iodo às mulheres em preconcepção, grávidas e mulheres que se encontrem em amamentação exclusiva 22 .…”