Iodine status in pregnant women and their newborns: are our babies at risk of iodine deficiency?

Travers, Cheryl; Guttikonda, Kamala; Norton, Carol A; Lewis, Peter; Mollart, Lyndall; Wiley, Veronica; Wilcken, Bridget; Eastman, Creswell J; Boyages, Steven

doi:10.5694/j.1326-5377.2006.tb00417.x

Cited by 64 publications

(55 citation statements)

References 14 publications

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“…In Belgium iodine status is characterized by iodine sufficiency in school-aged children and MID in pregnant women and in women of child-bearing age [20]; [21]. Despite that pregnant women are mildly iodine deficient the frequency of TSH values >5 mU/L in Belgium was low, considering the results from the centres using the same TSH assay, corroborating previous studies from mildly iodine deficient regions [26]. Interestingly, a clinical trial performed in Belgium on iodine supplementation in pregnant women did show differences in neonatal thyroglobulin concentrations but not in TSH levels of neonates born from women who received iodine supplements compared to those who did not [27].…”

Section: Discussionsupporting

confidence: 80%

“…A TSH frequency >5 mU/L below 3% has been reported in several mildly iodine deficient regions suggesting that neonatal TSH may not be sensitive enough to evaluate iodine status when iodine deficiency is mild. A study from Australia using a sensitive TSH assay found that only 2.2% of neonates had a TSH value >5% despite a median UIC of 85 µg/l among pregnant women [26]. In Belgium iodine status is characterized by iodine sufficiency in school-aged children and MID in pregnant women and in women of child-bearing age [20]; [21].…”

Section: Discussionmentioning

confidence: 99%

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Neonatal Thyroid-Stimulating Hormone Concentrations in Belgium: A Useful Indicator for Detecting Mild Iodine Deficiency?

et al. 2012

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It has been proposed that neonatal thyroid-stimulating hormone (TSH) concentrations are a good indicator of iodine deficiency in the population. A frequency of neonatal TSH concentrations above 5 mU/L below 3% has been proposed as the threshold indicating iodine sufficiency. The objective of the present study was to evaluate feasibility and usefulness of nation-wide neonatal TSH concentration screening results to assess iodine status in Belgium. All newborns born in Belgium during the period 2009–2011 (n = 377713) were included in the study, except those suffering from congenital hypothyroidism and premature neonates. The frequency of neonatal TSH concentrations above 5 mU/L from 2009 to 2011 in Belgium fluctuated between 2.6 and 3.3% in the centres using the same TSH assay. There was a significant inverse association between neonatal TSH level and birth weight. The longer the duration between birth and screening, the lower the TSH level. Neonatal TSH levels were significantly lower in winter than in spring or autumn and significantly lower in spring and summer than in autumn while significantly higher in spring compared to summer. In conclusion, despite that pregnant women in Belgium are mildly iodine deficient, the frequency of neonatal TSH concentrations above 5 mU/L was very low, suggesting that the neonatal TSH threshold proposed for detecting iodine deficiency needs to be re-evaluated. Although neonatal TSH is useful to detect severe iodine deficiency, it should not be recommended presently for the evaluation of iodine status in mildly iodine deficient regions.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Neonatal Thyroid-Stimulating Hormone Concentrations in Belgium: A Useful Indicator for Detecting Mild Iodine Deficiency?

et al. 2012

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“…The most vulnerable groups are pregnant and lactating women and their developing fetuses and neonates, given the crucial importance of iodine to ensure adequate levels of thyroid hormones (TH) for brain maturation. Iodine deficiency in pregnancy is a prevailing problem not only in developing countries, but also in western industrialized nations and other countries classified as free of iodine deficiency (Azizi et al, 2003, Travers et al, 2006, Leung et al, 2013). An explanation may be found in dietary changes.…”

mentioning

confidence: 99%

Influence of maternal thyroid hormones during gestation on fetal brain development

et al. 2017

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Thyroid hormones (TH) play an obligatory role in many fundamental processes underlying brain development and maturation. The developing embryo/fetus is dependent on maternal supply of TH. The fetal thyroid gland does not commence THs synthesis until mid gestation, and the adverse consequences of severe maternal TH deficiency on offspring neurodevelopment are well established. Recent evidence suggests that even more moderate forms of maternal thyroid dysfunction, particularly during early gestation, may have a long-lasting influence on child cognitive development and risk of neurodevelopmental disorders. Moreover, these observed alterations appear to be largely irreversible after birth. It is, therefore, important to gain a better understanding of the role of maternal thyroid dysfunction on offspring neurodevelopment in terms of the nature, magnitude, time-specificity, and context-specificity of its effects. With respect to the issue of context specificity, it is possible that maternal stress and stress-related biological processes during pregnancy may modulate maternal thyroid function. The possibility of an interaction between the thyroid and stress systems in the context of fetal brain development has, however, not been addressed to date. We begin this review with a brief overview of TH biology during pregnancy and a summary of the literature on its effect on the developing brain. Next, we consider and discuss whether and how processes related to maternal stress and stress biology may interact with and modify the effects of maternal thyroid function on offspring brain development. We synthesize several research areas and identify important knowledge gaps that may warrant further study. The scientific and public health relevance of this review relates to achieving a better understanding of the timing, mechanisms and contexts of thyroid programming of brain development, with implications for early identification of risk, primary prevention and intervention.

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“…To monitor the iodine status of a population, neonatal TSH whole blood concentration can be used as an indicator [60]. The proposed cut-off percentage below 3% of the TSH results >5 mU/L was shown to be not sensitive enough to detect MID [27,72]. The present study aims to reassess the recommended cut-off of >5 mU/L using ROC curve analysis.…”

Section: Discussionmentioning

confidence: 99%

“…However the cut-off of 5 mU/L recommended by the WHO has been criticized [69-71]. In addition, a percentage below 3% of the TSH results greater than 5 mU/L was found in populations with MID [27,72] failing to detect MID in those population. Since the proposed cut-off of percentage of TSH screening results >5 mU/L below 3% is not sensitive enough to detect MID, it should be reassessed.…”

Section: Introductionmentioning

confidence: 99%

Protocol of the PSYCHOTSH study: association between neonatal thyroid stimulating hormone concentration and intellectual, psychomotor and psychosocial development at 4–5 year of age: a retrospective cohort study

et al. 2014

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BackgroundSeveral European countries, including Belgium, still suffer from mild iodine deficiency. Thyroid stimulating hormone (TSH) concentration in whole blood measured at birth has been proposed as an indicator of maternal iodine status during the last trimester of pregnancy. It has been shown that mild iodine deficiency during pregnancy may affect the neurodevelopment of the offspring. In several studies, elevated TSH levels at birth were associated with suboptimal cognitive and psychomotor outcomes among young children. This paper describes the protocol of the PSYCHOTSH study aiming to assess the association between neonatal TSH levels and intellectual, psychomotor and psychosocial development of 4–5 year old children. The results could lead to a reassessment of the recommended cut-off levels of 5 > mU/L used for monitoring iodine status of the population.MethodsIn total, 380 Belgian 4–5 year old preschool children from Brussels and Wallonia with a neonatal blood spot TSH concentration between 0 and 15 mU/L are included in the study. For each sex and TSH-interval (0–1, 1–2, 2–3, 3–4, 4–5, 5–6, 6–7, 7–8, 8–9 and 9–15 mU/L), 19 newborns were randomly selected from all newborns screened by the neonatal screening centre in Brussels in 2008–2009. Infants with congenital hypothyroidism, low birth weight and prematurity were excluded from the study. Neonatal TSH concentration was measured by the Autodelphia method in dried blood spots, collected by heel stick on filter paper 3 to 5 days after birth. Cognitive abilities and psychomotor development are assessed using the Wechsler Preschool and Primary Scale of Intelligence - third edition - and the Charlop-Atwell Scale of Motor coordination. Psychosocial development is measured using the Child Behaviour Check List for age 1½ to 5 years old. In addition, several socioeconomic, parental and child confounding factors are assessed.ConclusionsThis study aims to clarify the effect of mild iodine deficiency during pregnancy on the neurodevelopment of the offspring. Therefore, the results may have important implications for future public health recommendations, policies and practices in food supplementation. In addition, the results may have implications for the use of neonatal TSH screening results for monitoring the population iodine status and may lead to the definition of new TSH cut-offs for determination of the severity of iodine status and for practical use in data reporting by neonatal screening centres.

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Iodine status in pregnant women and their newborns: are our babies at risk of iodine deficiency?

Cited by 64 publications

References 14 publications

Neonatal Thyroid-Stimulating Hormone Concentrations in Belgium: A Useful Indicator for Detecting Mild Iodine Deficiency?

Neonatal Thyroid-Stimulating Hormone Concentrations in Belgium: A Useful Indicator for Detecting Mild Iodine Deficiency?

Influence of maternal thyroid hormones during gestation on fetal brain development

Protocol of the PSYCHOTSH study: association between neonatal thyroid stimulating hormone concentration and intellectual, psychomotor and psychosocial development at 4–5 year of age: a retrospective cohort study

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