Jun 11, 2025
Excessive Iodine Intake in Pregnancy and Its Effect on the Neurodevelopment of Offspring - A Systematic Review
- Sraboni Sahoo1,
- Dr. Ashish Khobragade1
- 1All India Institute of Medical Sciences Raipur, India
Protocol Citation: Sraboni Sahoo, Dr. Ashish Khobragade 2025. Excessive Iodine Intake in Pregnancy and Its Effect on the Neurodevelopment of Offspring - A Systematic Review. protocols.io https://dx.doi.org/10.17504/protocols.io.36wgqqwz3gk5/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
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Created: June 11, 2025
Last Modified: June 11, 2025
Protocol Integer ID: 219918
Keywords: excessive iodine intake in pregnancy, excessive iodine intake during pregnancy, excess iodine intake during pregnancy, preventable neurodevelopmental abnormalities due to maternal iodine deficiency, excess iodine during pregnancy, maternal iodine deficiency, excessive iodine intake, excess iodine intake, deficiency of iodine, association of excess iodine, effect of excess iodine, excess iodine, iodine, normal urinary excretion of iodine, adverse thyroid function of both mother, thyroid dysfunction, adverse thyroid function, adverse neurodevelopment of offspring, adverse neurodevelopment, preventable neurodevelopmental abnormality, effect on the neurodevelopment, offspring neurodevelopment, subclinical hypothyroidism, neurodevelopment, pregnancy, brain development, deficiency, miscarriage
Abstract
Iodine is a micronutrient crucial for a child’s brain development during the first 1000 days of life. It is the leading cause of globally preventable neurodevelopmental abnormalities due to maternal iodine deficiency during pregnancy. The normal urinary excretion of iodine according to the World Health Organization is between 150-249 µg/L in pregnancy. Both deficiency and excess iodine during pregnancy are associated with adverse thyroid function of both mother and offspring. Excessive iodine intake during pregnancy has been associated with thyroid dysfunction, resulting in clinical and subclinical hypothyroidism, miscarriages, and preterm delivery. Deficiency of iodine during the gestational period has been proven to be associated with adverse neurodevelopment of offspring. However, excess iodine intake during pregnancy and its effect on the children’s neurodevelopment is a grey area of research. There is no systematic review regarding the association of excess iodine in pregnancy and its impact on offspring neurodevelopment. Hence, the purpose of this study is to assess the effect of excess iodine (>250 µg/L) during pregnancy on offspring neurodevelopment.
Materials
Eligibility criteria: Inclusion criteria: Studies which assessed iodine status in pregnancy by urinary iodine concentration (UIC), and UIC levels >250 µg/L. Studies evaluated the neurodevelopment of the offspring of respective pregnant mothers. Only prospective cohort studies will be included. Studies published in the English language. Exclusion criteria: Studies that reported only iodine deficiency (UIC <150 µg/L) in pregnancy will be excluded. Studies do not assess the neurodevelopment of offspring. Information sources: The search will be conducted in the PubMed, Scopus, and Google Scholar databases.
Troubleshooting
Method and Materials
Eligibility criteria
Inclusion criteria: Studies which assessed iodine status in pregnancy by urinary iodine concentration (UIC), and UIC levels >250 µg/L.
Studies evaluated the neurodevelopment of the offspring of respective pregnant mothers.
Only prospective cohort studies will be included.
Studies published in the English language.
Exclusion criteria
Studies that reported only iodine deficiency (UIC <150 µg/L) in pregnancy will be excluded.
Studies do not assess the neurodevelopment of offspring.
Information sources
The search will be conducted in the PubMed, Scopus, and Google Scholar databases.
Search
The PECOS strategy will be adopted to identify the research question.
Population (P) will be pregnant women and their children.
Exposure (E) will be excessive consumption of iodine.
Control (C) will be pregnant women with normal iodine levels.
Outcome (O) will be the effect on neurodevelopment of offspring.
Study design (S) will be prospective cohort study design.
Strategy: (((pregnancy) OR (pregnant women) OR (gestation) OR (expecting women) OR (pregnant mothers) OR (trimester)) AND ((excess iodine) OR (iodine) OR (iodine intake) OR (excess UIC) OR urinary iodine concentration OR (excess iodine intake)) AND ((neurodevelopment) OR (cognition) OR (IQ) OR (language) OR (intelligence quotient) OR (mental development) OR (neuro cognitive)))
The search will be conducted within 6 months.
Selection of Studies
First, the titles of the articles will be read, followed by the abstracts, and finally, a full-text appraisal will be conducted by the two independent reviewers. If the study fulfills the inclusion criteria, it will be selected for this research.
Data Extraction
The data for this research will be extracted from the articles, including authors, year of publication, sample size, trimester of pregnancy, Urinary Iodine Concentration (UIC), scale used for detecting cognition, neurodevelopmental status of offspring, age of offspring, main findings, and conclusion.
Outcomes
The effect of excess iodine intake (measured by Urinary Iodine Concentration (UIC >250 µg/L)) by pregnant women on the neurodevelopment of offspring will be assessed.
Additional Outcome
Not applicable.
Risk of Bias
For assessing the quality of studies, the Newcastle-Ottawa Scale, adapted for Cohort studies, will be used.
Strategy for Data Synthesis
We will investigate the impact of excessive iodine intake during pregnancy on various neurodevelopmental domains in children, including motor, language, cognitive, and social development. We will use a narrative approach to synthesize the main findings of the study. Tables and graphs will be used to present the findings of the study.