The effect of iodine supplementation in pregnancy on early childhood neurodevelopment and clinical outcomes: results of an aborted randomised placebo-controlled trial

Abstract

BackgroundConcern that mild iodine deficiency in pregnancy may adversely affect neurodevelopment of offspring has led to recommendations for iodine supplementation in the absence of evidence from randomised controlled trials. The primary objective of the study was to investigate the effect of iodine supplementation during pregnancy on childhood neurodevelopment. Secondary outcomes included pregnancy outcomes, maternal thyroid function and general health.MethodsWomen with a singleton pregnancy of fewer than 20 weeks were randomly assigned to iodine (150 μg/d) or placebo from trial entry to birth. Childhood neurodevelopment was assessed at 18 months by using Bayley Scales of Infant and Toddler Development (Bayley-III). Iodine status and thyroid function were assessed at baseline and at 36 weeks’ gestation. Pregnancy outcomes were collected from medical records.ResultsThe trial was stopped after 59 women were randomly assigned following withdrawal of support by the funding body. There were no differences in childhood neurodevelopmental scores between the iodine treated and placebo groups. The mean cognitive, language and motor scores on the Bayley-III (iodine versus placebo, respectively) were 99.4 ± 12.2 versus 101.7 ± 8.2 (mean difference (MD) −2.3, 95 % confidence interval (CI) −7.8, 3.2; P = 0.42), 97.2 ± 12.2 versus 97.9 ± 11.5 (MD −0.7, 95 % CI −7.0, 5.6; P = 0.83) and 93.9 ± 10.8 versus 92.4 ± 9.7 (MD 1.4, 95 % CI −4.0, 6.9; P = 0.61), respectively. No differences were identified between groups in any secondary outcomes.ConclusionsIodine supplementation in pregnancy did not result in better childhood neurodevelopment in this small trial. Adequately powered randomised controlled trials are needed to provide conclusive evidence regarding the effect of iodine supplementation in pregnancy.Trials registrationThe trial was registered with the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au. The registration number of this trial is ACTRN12610000411044. The trial was registered on 21 May 2010.

Iodine supplementation in pregnancy – is it time?

“…Further randomized controlled trials are clearly desirable here, however key problems exist. A recent trial ended prematurely due to unforeseen cessation of funding as the Australian government initiated a recommendation that iodine supplements should be routinely used by all pregnant women. Trials of iodine supplementation in women with mild‐moderate iodine deficiency may now no longer be ethically viable with regard to the control group.…”

Iodine, ingesting or not?

“…In the last 30 years, National Health and Nutrition Examination Survey (NHANES) showed that there is a decreased of 50% in the iodine intake [16]. The Japan and China are the countries that have lowest world rate of perinatal mortality because one of sources iodine intake is through of seaweed and the women intake a big quantity of seaweed compared to other women of the world [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Seaweed has a capacity of accumulated most iodine that sea water, however the distance from the sea also influences the iodine content of plants, how much major the distance, lower the concentration of iodine [18].…”

“…Besides, the ability of perspire is coordinated by iodine and patients with cancer has difficulty perspiring due to iodine deficiency in the skin. Increase of various types of cancer is linked with iodine deficiency, minerals and vitamins that are lacking in the sun as selenium and magnesium [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Survival rates of cancer are the same as those of the last 70 years [21] even with all the advances like mammograms, surgery, chemotherapy and radiotherapy.…”

“…In this baseline, there are six systematic reviews published in the last 6 years beyond WHO/ UNICEF [30] encourage the safe use iodine in the dosages of 200 µg/day during in pregnancy and 250 µg/day in lactating women [24][25][26][27][28][29][30][31]. In contrast, there is a small trial showed that the Iodine supplementation in pregnancy did not result in better childhood neurodevelopment, although the dosage of iodine it was just 150 µg/day [32]. On the other hand, one study Australian showed that of 396 healthcare providers only 71% were aware of the National Health and Medical Research Council's recommendation for iodine supplementation, (38%) were aware of the recommended dose or and (44%) duration [33].…”

Iodine and Pregnancy—A Qualitative Study Focusing on Dietary Guidance and Information

“…There is a sustained debate on the ethical implications of a randomised controlled trial of iodine supplementation in pregnancy, in parallel with concerns over the adverse effects of salt and the conflicted message that salt iodisation would convey [20,21]. There are a range of other strategies to tackle iodine insufficiency, including updating dietary recommendations, introducing mandatory salt fortification, and new nutritional education strategies aiming to increase awareness and promote iodine rich foods [22,23].…”