Quality & Quantity

, Volume 52, Issue 3, pp 1423–1435 | Cite as

Does the iodized salt therapy of pregnant mothers increase the children IQ? Empirical evidence of a statistical study based on permutation tests

  • Massimiliano Giacalone
  • Agata Zirilli
  • Mariacarla Moleti
  • Angela Alibrandi


The nutritional iodine deficiency disorders are still a major health problem in industrialized countries, but they are completely preventable by means of iodine prophylaxis. Iodine is essential for thyroid hormone (TH) synthesis and TH is required for normal brain development. Gestational iodine supplementation may improve infant cognitive development. In this study we aimed at evaluating the intelligence quotient of children born to mothers with different levels of iodine supplementation, with or without the administration of levothyroxine (LT4), prior to and during pregnancy. In particular we focused our attention on some mother–child pairs and we compared them according to iodized salt consumption and LT4 treatment. In this specific context, NPC test was applied to compare four groups of children, defined on the basis of maternal history related to iodized salt consumption and LT4 treatment. The results show that the deficit in functionality cognitive (in terms of intelligence quotient) is significantly higher in the children of mothers that does not make supplementation of iodized salt. This shows how a lack of iodine can hinder children in reaching their full intellectual potential. From a methodological point of view, our research showed the utility of the Non Parametric Combination test (NPC test) into analyze data concerning medical research.


Neurocognitive development Iodine nutrition Thyroid status Comparative analysis Permutation test 


Compliance with ethical standards

Conflicts of interest

The authors declare that there is no conflict of interest.

Human and animals rights

The study involved mother–child pairs.

Informed consent

All participants gave their informed consent (such as specified in subsection 2.2).


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Copyright information

© Springer Science+Business Media B.V. 2017

Authors and Affiliations

  1. 1.Department of Economics and StatisticsUniversity of Naples Federico IINaplesItaly
  2. 2.Department of Economics, Section of Statistical and Mathematical SciencesUniversity of MessinaMessinaItaly
  3. 3.Department of Clinical and Experimental Medicine, AOU Policlinico G. MartinoUniversity of MessinaMessinaItaly

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