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Noncompliance to iodine supplementation recommendation is a risk factor for iodine insufficiency in Portuguese pregnant women: results from the IoMum cohort

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Abstract

Purpose

After a recommendation for iodine supplementation in pregnancy has been issued in 2013 in Portugal, there were no studies covering iodine status in pregnancy in the country. The aim of this study was to assess iodine status in pregnant women in Porto region and its association with iodine supplementation.

Methods

A cross-sectional study was conducted at Centro Hospitalar Universitário São João, Porto, from April 2018 to April 2019. Pregnant women attending the 1st trimester ultrasound scan were invited to participate. Exclusion criteria were levothyroxine use, gestational age < 10 and ≥ 14 weeks, non-evolutive pregnancy at recruitment and non-signing of informed consent. Urinary iodine concentration (UIC) was measured in random spot urine by inductively coupled plasma-mass spectrometry.

Results

Median UIC was 104 μg/L (IQR 62–189) in the overall population (n = 481) of which 19% had UIC < 50 µg/L. Forty three percent (n = 206) were not taking an iodine-containing supplement (ICS) and median UIC values were 146 µg/L (IQR 81–260) and 74 µg/L (IQR 42–113) in ICS users and non-users, respectively (p < 0.001). Not using an ICS was an independent risk factor for iodine insufficiency [adjusted OR (95% CI) = 6.00 (2.74, 13.16); p < 0.001]. Iodised salt use was associated with increased median iodine-to-creatinine ratio (p < 0.014).

Conclusions

A low compliance to iodine supplementation recommendation in pregnancy accounted for a mild-to-moderately iodine deficiency. Our results evidence the need to support iodine supplementation among pregnant women in countries with low household coverage of iodised salt.

Trial registration number NCT04010708, registered on the 8th July 2019.

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Data availability

The data sets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

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Acknowledgements

With this work we intend to honour Professor Nuno Montenegro for his deep dedication to women's health, always valuing the importance of science for that final good. It was with great regret that we saw him leave too soon. Without the dedication of Professor Nuno Montenegro, the IoMum study would not have been possible. The authors would also like to acknowledge the kind participation of all pregnant women and the support of recruitment activities by health-care professionals from the Department of Obstetrics of Centro Hospitalar Universitário S. João, Porto, Portugal.

Funding

This article was supported by National Funds through FCT—Fundação para a Ciência e a Tecnologia,I.P., within CINTESIS, R&D Unit (reference UIDB/4255/2020); LAQV (reference UIDB/50006/2020) and through FCT postdoctoral fellowship (V.C.F., grant number SFRH/BPD/109153/2015).

Author information

Authors and Affiliations

  1. CINTESIS@RISE, Department Biomedicine, Unit of Biochemistry, Faculty of Medicine, University of Porto, 4200-319, Porto, Portugal

    C. Matta Coelho, J. Guimarães, I. Bracchi, C. Pinheiro & E. Keating

  2. CINTESIS@RISE, Faculty of Medicine, University of Porto, Porto, Portugal

    N. Xavier Moreira & J. Costa Leite

  3. Fluminense Federal University, Niterói, Rio de Janeiro, Brasil

    N. Xavier Moreira

  4. Faculdade de Ciências da Nutrição e Alimentação, Universidade do Porto, Porto, Portugal

    P. Ferreira

  5. CINTESIS@RISE, Nutrition and Metabolism, NOVA Medical School│FCM, Universidade Nova de Lisboa, Porto, Portugal

    D. Pestana, I. Barreiros Mota, A. Moreira-Rosário & C. Calhau

  6. Medicina Laboratorial Dr. Carlos Torres, Porto, Portugal

    A. Cortez

  7. Department of Obstetrics, Centro Hospitalar Universitário S. João, Porto, Portugal

    C. Prucha, C. Martins & C. Ramalho

  8. REQUIMTE//LAQV, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal

    E. Pinto & A. Almeida

  9. Department of Environmental Health, School of Health, P.Porto, Porto, Portugal

    E. Pinto

  10. REQUIMTE/LAQV, Instituto Superior de Engenharia, Politécnico do Porto, Porto, Portugal

    C. Delerue-Matos & V. Cruz Fernandes

  11. CINTESIS@RISE, Department of Community Medicine, Information and Health Decision Sciences (MEDCIDS), Faculty of Medicine, University of Porto, Porto, Portugal

    C. C. Dias & L. F. Ribeiro de Azevedo

  12. Department of Ginecology-Obstetrics and Pediatrics, Faculty of Medicine, University of Porto, Porto, Portugal

    C. Ramalho

  13. Instituto de Investigação e Inovação em Saúde, i3S, Universidade Do Porto, Porto, Portugal

    C. Ramalho

  14. Division of Climate and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway

    A.-L. Brantsæter

Authors
  1. C. Matta Coelho
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  2. J. Guimarães
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  3. I. Bracchi
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  4. N. Xavier Moreira
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  6. P. Ferreira
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  22. J. Costa Leite
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  23. E. Keating
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Contributions

CMC: conceptualization, methodology, investigation, formal analysis, writing—original draft, visualization, funding acquisition; JG: Investigation; IB: investigation, writing—review and editing; NXM: investigation, writing—review and editing; CP: investigation; PF: investigation; DP: investigation, methodology, funding acquisition; IBM: investigation; AC: resources; CP: resources; CM: resources; EP: investigation, writing—review and editing; AA: investigation, writing—review and editing, funding acquisition; CD-M: investigation, funding acquisition; CCD: formal analysis, writing—review and editing; AM-R: methodology, formal analysis, writing—review and editing; LFR de A: conceptualization, methodology, writing—review and editing; VCF: investigation, formal analysis, writing—review and editing, funding acquisition; CR: methodology, resources, investigation, writing—review and editing; CC: conceptualization, methodology, funding acquisition; A-LB: methodology, supervision, writing—review and editing; JCL: conceptualization, methodology, supervision; EK: conceptualization, methodology, supervision, project administration, funding acquisition, writing—review and editing.

Corresponding author

Correspondence to E. Keating.

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Conflict of interest

The authors have no relevant financial or non-financial interests to disclose. The authors have no competing interests to declare that are relevant to the content of this article. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. The authors have no financial or proprietary interests in any material discussed in this article.

Ethics approval

This study was performed in line with the principles of the Declaration of Helsinki. All procedures were approved by the Ethics Committee of Centro Hospitalar Universitário São João. All participants were included upon informed consent signature.

Informed consent

Informed consent was obtained from all individual participants included in the study.

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Matta Coelho, C., Guimarães, J., Bracchi, I. et al. Noncompliance to iodine supplementation recommendation is a risk factor for iodine insufficiency in Portuguese pregnant women: results from the IoMum cohort. J Endocrinol Invest 45, 1865–1874 (2022). https://doi.org/10.1007/s40618-022-01813-7

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