Effect of iodine supplementation in pregnant women on child neurodevelopment: a randomised, double-blind, placebo-controlled trial

Gowachirapant, Sueppong; Jaiswal, Nidhi; Melse‐Boonstra, Alida; Galetti, Valeria; Stinca, Sara; Mackenzie, Ian C.; Thomas, Simmy; Thomas, Tinku; Winichagoon, Pattanee; Srinivasan, Krishnamachari; Zimmermann, Michael

doi:10.1016/s2213-8587(17)30332-7

Cited by 117 publications

(173 citation statements)

References 27 publications

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“…Several observational studies suggest an association between mild iodine deficiency during fetal life and poor educational level, motor skills, or verbal abilities in children 3-12 years of age [5,6,44,45]. However, this was not confirmed in randomized controlled trials of iodine supplementation of pregnant women with mild iodine deficiency [8,42], possibly due to lower than expected prevalence of iodine deficiency in the population studied in one trial [8] or due to low sample size in the other trial [42]. At the same time, other observational studies have indicated the opposite, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Moderate-to-severe iodine deficiency during pregnancy increases the risk of cognitive impairment in the offspring [1][2][3][4]. Observational studies suggest that even mild iodine deficiency during pregnancy may negatively affect verbal intelligence quotient and educational level in their children [5][6][7], although a causal relation could not be confirmed in a recent randomized controlled trial of iodine supplementation in pregnant women with mild iodine deficiency [8].…”

Section: Introductionmentioning

confidence: 99%

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Iodine deficiency in pregnant women in Sweden: a national cross-sectional study

et al. 2019

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Purpose Voluntary salt iodization at 50 mg/kg salt ensures adequate iodine nutrition in Swedish school-aged children, but iodine status in pregnant women is uncertain. Methods We conducted a cross-sectional national study of 743 pregnant women, at median gestational age of 23 weeks (IQR 9, 38), recruited from maternal health care centers. We measured: urinary iodine concentration (UIC) and urinary creatinine concentration in spot urine samples; thyroglobulin (Tg), thyroid-stimulating hormone (TSH), and total thyroxine (tT4) on dried blood spots (DBS); and thyreoperoxidase antibodies in serum samples. Data on dietary supplement use were obtained, and women were classified as supplement users (consuming multivitamins containing ≥ 150 µg iodine/day) and non-supplement users (no supplements or < 150 µg iodine/day from supplements). Results Overall median UIC [bootstrapped 95% confidence interval (CI)] was 101 µg/L (95, 108; n = 737): 149 µg/L (132, 164) in supplement users (n = 253) and 85 µg/L (79, 92) in non-supplement users (n = 440) (p < 0.001). Overall geometric mean DBS-Tg (95% CI) was 22.1 μg/L (20.8, 23.5; n = 675) and the prevalence of elevated DBS-Tg was 19%. DBS-Tg was lower in supplement users (n = 229) than in non-supplement users (n = 405) (19.1 vs 24.4 μg/L, p < 0.001). DBS-TSH, DBS-tT4, and S-TPOab positivity did not differ between the two groups. Conclusions Pregnant women in Sweden have inadequate iodine nutrition. Women not taking iodine supplements containing ≥ 150 µg iodine/day are affected by mild iodine deficiency and are at higher risk for increased thyroid activity, while maintaining euthyroidism. Iodine intake should be improved in women both before and after conception by promotion of iodized salt instead of non-iodized salt. We urge regular monitoring of iodine status in the general Swedish population, as well as in risk groups.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Iodine deficiency in pregnant women in Sweden: a national cross-sectional study

et al. 2019

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“…We calculated pooled effect sizes if at least five studies reported an intervention versus control group comparison in any category of intervention (eg, nutritional supplementation and promotion of responsive care and learning opportunities). We applied the same criterion to stratified 29 Ong et al 37 Jeon et al 41 Lind et al 31 Rosado et al 15 Oelofse et al 52 Nahar et al 48 Smuts et al 62 Husaini et al 50 Phuka et al 21 Maleta et al 17 Krebs et al 54 Bauserman et al 55 Faber et al 14 Hess et al 16 Dewey et al 20 77 Luby et al 23 Stewart et al 22 Gladstone et al 61 Lees et al 80 Hallamaa et al 82 Tomlinson et al 78 Tumwine et al 79 Dewey et al 20 Adu-Afarwuah et al 18 Ashorn et al 19 Zhang et al 59 Thomas et al 60 Gowachirapant et al 51 Hamadani et al 35 Jacobson et al 58 Schmidt et al 53 Hanieh 36 Zhu et al 56 Nguyen et al 34 Christian et al 40 Gonzalez-Casano 87 Tofail et al 49 In utero 3 6 9 12 15 18 Months Years 64 Nahar et al 48 Hamadani et al 70 Tofail et al…”

Section: Data Collection and Analysismentioning

confidence: 99%

Do effects of early life interventions on linear growth correspond to effects on neurobehavioural development? A systematic review and meta-analysis

Prado

Larson

Cox

et al. 2019

The Lancet Global Health

138

146

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Background Faltering in linear growth and neurobehavioural development during early childhood are often assumed to have common causes because of their consistent association. This notion has contributed to a global focus on the promotion of nutrition during pregnancy and childhood to improve both conditions. Our aim was to assess whether effects of interventions on linear growth are associated with effects on developmental scores and to quantify these associations.Methods In this systematic review and meta-analysis, we included randomised trials done during pregnancy and in children aged 0-5 years that reported effects of any intervention on length-for-age or height-for-age Z scores (LAZ or HAZ) and on any of the following outcomes: motor, cognitive or mental, language, and social-emotional or behavioural development. We searched MEDLINE (Ovid), CINAHL (EBSCO), and PsycINFO (EBSCO) from database inception to June 25, 2019. Study-level data were extracted and, when required, authors were contacted for missing information. We calculated weighted meta-regression coefficients of the association between standardised effect sizes of interventions on LAZ or HAZ and developmental outcome scores and calculated pooled effect sizes for different types of intervention.Findings Of the 7207 studies identified, we included 75 studies with 122 comparisons between intervention and control groups and outcomes reported for 72 275 children. Across all interventions, effect sizes on LAZ or HAZ were significantly associated with effect sizes on social-emotional scores (β 0·23, 95% CI 0·05 to 0·41; p=0·02), but not on cognitive (0·18, -0·36 to 0·72; p=0·51), language (0·12, -0·07 to 0·31; p=0·21), or motor development scores (0·23, -0·05 to 0·50; p=0·11). In studies that provided nutritional supplements, we observed positive significant pooled effect sizes on all five outcomes of LAZ or HAZ (effect size 0·05, 95% CI 0·01-0·09; p=0·01; n=50), cognitive or mental (0·06, 0·03-0·10; p<0·01; n=38), language (0·08, 0·03-0·13; p=0·01; n=21), motor (0·08, 0·04-0·12; p<0·01; n=41), and social-emotional (0·07, 0·02-0·12; p=0·01; n=20) scores. The effect sizes of nutritional supplementation on LAZ or HAZ scores were significantly associated with effect sizes on cognitive (β 0·40, 95% CI 0·04-0·77; p=0·049) and motor (0·43, 0·11-0·75; p=0·01) scores. In the 14 interventions promoting responsive care and learning opportunities, the pooled effect size on LAZ or HAZ score was not significant (-0·01, 95% CI -0·07 to 0·05; p=0·74), but pooled effect sizes on cognitive, language, and motor scores were 4 to 5 times larger (range 0·38-0·48) than the pooled effect sizes of nutritional supplementation (0·05-0·08). Interpretation In nutritional supplementation interventions, improvements in linear growth were associated with small improvements in child development, whereas nurturing and stimulation interventions had significant effects on child development but no effectson linear growth. The determinants of linear growth and neurodevelopment are only partly ...

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“…Three small randomized studies have examined the effects of prenatal iodine supplementation on postpartum thyroiditis, but none of the studies observed a difference in frequency or severity of the condition . In a randomized trial, pregnant women were given 200 μg iodine/day or placebo until delivery; no differences were observed in maternal thyroid function tests, thyroid volume, or TPOAb between groups during pregnancy and at 6 weeks postpartum . Autoimmune thyroid disease during pregnancy has been recently reviewed in depth…”

Section: Thyroid Disorders Associated With Iodine Excessmentioning

confidence: 99%

“…[163][164][165] In a randomized trial, pregnant women were given 200 g iodine/day or placebo until delivery; no differences were observed in maternal thyroid function tests, thyroid volume, or TPOAb between groups during pregnancy and at 6 weeks postpartum. 166 Autoimmune thyroid disease during pregnancy has been recently reviewed in depth. 115…”

Section: Postpartum Thyroiditismentioning

confidence: 99%

Excess iodine intake: sources, assessment, and effects on thyroid function

Farebrother

Zimmermann

Andersson

2019

Annals of the New York Academy of Sciences

204

131

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Iodine is essential for thyroid hormone synthesis. High iodine intakes are well tolerated by most healthy individuals, but in some people, excess iodine intakes may precipitate hyperthyroidism, hypothyroidism, goiter, and/or thyroid autoimmunity. Individuals with preexisting thyroid disease or those previously exposed to iodine deficiency may be more susceptible to thyroid disorders due to an increase in iodine intake, in some cases at intakes only slightly above physiological needs. Thyroid dysfunction due to excess iodine intake is usually mild and transient, but iodine‐induced hyperthyroidism can be life‐threatening in some individuals. At the population level, excess iodine intakes may arise from consumption of overiodized salt, drinking water, animal milk rich in iodine, certain seaweeds, iodine‐containing dietary supplements, and from a combination of these sources. The median urinary iodine concentration (UIC) of a population reflects the total iodine intake from all sources and can accurately identify populations with excessive iodine intakes. Our review describes the association between excess iodine intake and thyroid function. We outline potential sources of excess iodine intake and the physiological responses and consequences of excess iodine intakes. We provide guidance on choice of biomarkers to assess iodine intake, with an emphasis on the UIC and thyroglobulin.

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Effect of iodine supplementation in pregnant women on child neurodevelopment: a randomised, double-blind, placebo-controlled trial

Cited by 117 publications

References 27 publications

Iodine deficiency in pregnant women in Sweden: a national cross-sectional study

Iodine deficiency in pregnant women in Sweden: a national cross-sectional study

Do effects of early life interventions on linear growth correspond to effects on neurobehavioural development? A systematic review and meta-analysis

Excess iodine intake: sources, assessment, and effects on thyroid function

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