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

Shao J Zhou, Sheila A Skeaff, Philip Ryan, Lex W Doyle, Peter J Anderson, Louise Kornman, Andrew J Mcphee, Lisa N Yelland, Maria Makrides

Journal: Trials 2016;16():563

PMID: 26654905

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Abstract

BACKGROUND

Concern 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.

METHODS

Women 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.

RESULTS

The 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.

CONCLUSIONS

Iodine 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 REGISTRATION

The 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.

Address: Women's & Children's Health Research Institute, 72 King William Road, North Adelaide, SA, 5006, Australia. [email protected].; School of Agriculture, Food & Wine, University of Adelaide, Waite Campus, Waite Road, Urrbrae, SA, 5064, Australia. [email protected].; Department of Human Nutrition, University of Otago, PO Box 56, Dunedin, 9054, New Zealand. [email protected].; School of Population Health, University of Adelaide, 178 North Terrace, Adelaide, SA, 5005, Australia. [email protected].; Department of Obstetrics and Gynaecology, Royal Women's Hospital, Cnr of Flemington Road and Grattan Street, University of Melbourne, Melbourne, VIC, 3052, Australia. [email protected].; Clinical Sciences, Murdoch Childrens Research Institute, Flemington Road, Melbourne, VIC, 3052, Australia. [email protected].; Department of Paediatrics, University of Melbourne, 50 Flemington Road, Melbourne, VIC, 3052, Australia. [email protected].; Clinical Sciences, Murdoch Childrens Research Institute, Flemington Road, Melbourne, VIC, 3052, Australia. [email protected].; Department of Paediatrics, University of Melbourne, 50 Flemington Road, Melbourne, VIC, 3052, Australia. [email protected].; Department of Obstetrics and Gynaecology, Royal Women's Hospital, Cnr of Flemington Road and Grattan Street, University of Melbourne, Melbourne, VIC, 3052, Australia. [email protected].; Women's and Children's Health Network, 72 King William Road, North, Adelaide, SA, 5006, Australia. [email protected].; Women's & Children's Health Research Institute, 72 King William Road, North Adelaide, SA, 5006, Australia. [email protected].; School of Population Health, University of Adelaide, 178 North Terrace, Adelaide, SA, 5005, Australia. [email protected].; Women's & Children's Health Research Institute, 72 King William Road, North Adelaide, SA, 5006, Australia. [email protected].; School of Paediatrics & Reproductive Health, University of Adelaide, Frome Road, Adelaide, SA, 5005, Australia. [email protected].; South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia. [email protected].

DOI: 10.1186/s13063-015-1080-8

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MeSH Terms: Adult, Age Factors, Australia, Child Development, Child Language, Cognition, Dietary Supplements, Double-Blind Method, Early Termination of Clinical Trials, Female, Humans, Infant, Male, Maternal Health, Motor Activity, Nervous System, Neuropsychological Tests, New Zealand, Potassium Iodide, Pregnancy, Pregnancy Complications, Prenatal Care, Research Design, Thyroid Function Tests, Thyroid Gland, Time Factors, Treatment Outcome, Young Adult