Skip to main content

Iodine status of postpartum women and their infants in Australia after the introduction of mandatory iodine fortification

  • Dao Huynh (a1), Dominique Condo (a2), Robert Gibson (a1) (a2), Beverly Muhlhausler (a1) (a2), Philip Ryan (a3), Sheila Skeaff (a4), Maria Makrides (a1) (a2) (a5) and Shao J. Zhou (a1) (a2)...

Mandatory I fortification in bread was introduced in Australia in 2009 in response to the re-emergence of biochemical I deficiency based on median urinary I concentration (UIC)<100 µg/l. Data on the I status of lactating mothers and their infants in Australia are scarce. The primary aim of this study was to assess the I status, determined by UIC and breast milk I concentration (BMIC), of breast-feeding mothers in South Australia and UIC of their infants. The secondary aim was to assess the relationship between the I status of mothers and their infants. The median UIC of the mothers (n 686) was 125 (interquartile range (IQR) 76–200) µg/l and median BMIC (n 538) was 127 (IQR 84–184) µg/l. In all, 38 and 36 % of the mothers had a UIC and BMIC below 100 µg/l, respectively. The median UIC of infants (n 628) was 198 (IQR 121–296) µg/l, and 17 % had UIC<100 µg/l. Infant UIC was positively associated with maternal UIC (β 0·26; 95 % CI 0·14, 0·37, P<0·001) and BMIC (β 0·85; 95 % CI 0·66, 1·04, P<0·001) at 3 months postpartum after adjustment for gestational age, parity, maternal secondary and further education, BMI category and infant feeding mode. The adjusted OR for infant UIC<100 µg/l was 6·49 (95 % CI 3·80, 11·08, P<0·001) in mothers with BMIC<100 µg/l compared with those with BMIC≥100 µg/l. The I status of mothers and breast-fed infants in South Australia, following mandatory I fortification, is indicative of I sufficiency. BMIC<100 µg/l increased the risk of biochemical I deficiency in breast-fed infants.

Corresponding author
* Corresponding author: Dr S. J. Zhou, fax +61 8 8303 7135, email
Hide All
1. Mullur, R, Liu, YY & Brent, GA (2014) Thyroid hormone regulation of metabolism. Physiol Rev 94, 355382.
2. Stagnaro-Green, A & Pearce, EN (2013) Iodine and pregnancy: a call to action. Lancet 382, 292293.
3. United Nations International Children’s Emergency Fund (2008) Sustainable elimination of iodine deficiency. (accessed December 2014).
4. Zimmermann, MB, Gizak, M, Abbott, K, et al. (2015) Iodine deficiency in pregnant women in Europe. Lancet Diabetes Endocrinol 3, 672674.
5. Eastman, CJ & Zimmermann, MB (2009) Iodine deficiency disorders. (accessed February 2011).
6. Food Standards Australia and New Zealand (2008) Proposal P1003 – mandatory iodine fortification for Australia, approved report, Food Standards Australia and New Zealand, Canberra. (accessed December 2014).
7. Australian Bureau of Statistics (2013) Australian Health Survey: biomedical results for Nutrients 2011–12. (accessed December 2014).
8. Chan, SS, Hams, G, Wiley, V, et al. (2003) Postpartum maternal iodine status and the relationship to neonatal thyroid function. Thyroid 13, 873876.
9. Gunton, JE, Hams, G, Fiegert, M, et al. (1999) Iodine deficiency in ambulatory participants at a Sydney teaching hospital: is Australia truly iodine replete? Med J Aust 171, 467470.
10. Andersson, M, de Benoist, B, Delange, F, et al. (2007) Prevention and control of iodine deficiency in pregnant and lactating women and in children less than 2-years-old: conclusions and recommendations of the Technical Consultation. Public Health Nutr 10, 16061611.
11. Axford, S, Charlton, K, Yeatman, H, et al. (2011) Improved iodine status in breastfeeding women following mandatory fortification. Aust N Z J Public Health 35, 579580.
12. World Health Organization (2007) Assessment of iodine deficiency disorders and monitoring their elimination. (accessed December 2014).
13. Bazrafshan, HR, Mohammadian, S, Ordookhani, A, et al. (2005) An assessment of urinary and breast milk iodine concentrations in lactating mothers from Gorgan, Iran, 2003. Thyroid 15, 11651168.
14. Hashemipour, M, Nasri, P, Hovsepian, S, et al. (2010) Urine and milk iodine concentrations in healthy and congenitally hypothyroid neonates and their mothers. Endokrynol Pol 61, 371376.
15. Dold, S, Zimmermann, MB, Baumgartner, J, et al. (2016) A dose-response crossover iodine balance study to determine iodine requirements in early infancy. Am J Clin Nutr 104, 620628.
16. Semba, RD & Delange, F (2001) Iodine in human milk: perspectives for infant health. Nutr Rev 59, 269278.
17. Condo, D, Skeaff, S, Ryan, P, et al. (2015) Relationship between maternal and infant thyroid function: a large prospective cohort study. J Paediatr Child Health 51, 59.
18. Huynh, D, Condo, D, Gibson, R, et al. (2017) Comparison of breast-milk iodine concentration of lactating women in Australia pre and post mandatory iodine fortification. Public Health Nutr 20, 1217.
19. Huynh, D, Zhou, SJ, Gibson, R, et al. (2015) Validation of an optimized method for the determination of iodine in human breast milk by inductively coupled plasma mass spectrometry (ICPMS) after tetramethylammonium hydroxide extraction. J Trace Elem Med Biol 29, 7582.
20. National Health & Medical Research Council (2010) NHMRC public statement: iodine supplementation for pregnant and breastfeeding women. (accessed July 2012).
21. Semba, RD & Delange, F (2002) Iodine in human milk: perspectives for infant health. Nutr Rev 59, 269278.
22. Liu, L, Wang, D, Liu, P, et al. (2015) The relationship between iodine nutrition and thyroid disease in lactating women with different iodine intakes. Br J Nutr 114, 14871495.
23. Wang, Y, Zhang, Z, Ge, P, et al. (2009) Iodine status and thyroid function of pregnant, lactating women and infants (0-1 yr) residing in areas with an effective Universal Salt Iodization program. Asia Pac J Clin Nutr 18, 3440.
24. Johner, SA, Thamm, M, Schmitz, R, et al. (2016) Examination of iodine status in the German population: an example for methodological pitfalls of the current approach of iodine status assessment. Eur J Nutr 55, 12751282.
25. Zou, Y, Ding, G, Lou, X, et al. (2015) A study on the influencing factors of urinary iodine concentration and the relationship between iodised salt concentration and urinary iodine concentration. Br J Nutr 113, 142146.
26. Nazeri, P, Mirmiran, P, Hedayati, M, et al. (2016) Can postpartum maternal urinary iodine be used to estimate iodine nutrition status of newborns? Br J Nutr 115, 12261231.
27. Pouessel, G, Damie, R, Soudan, B, et al. (2008) Status of iodine nutrition of children until 1 year: consequences on the thyroid function. Arch Pediatr 15, 12761282.
28. Yang, J, Zheng, H, Li, X, et al. (2014) Assessment of iodine status and associated factors in vulnerable populations in Henan Province, China, in 2012. Asia Pac J Clin Nutr 23, 626633.
29. Asfaw, A (2007) Micronutrient deficiency and the prevalence of mothers’ overweight/obesity in Egypt. Econ Hum Biol 5, 471483.
30. Boron, WF & Boulpaep, EL (2009) Thyroid hormone synthesis. In Medical Physiology: A Cellular and Molecular Approach, 2nd ed., pp. 10441056 [WF Boron and EL Boulpaep, editors]. Philadelphia, PA: Saunders/Elsevier.
31. Gordon, JH, Leung, AM, Hale, AR, et al. (2014) No difference in urinary iodine concentrations between Boston-area breastfed and formula-fed infants. Thyroid 24, 13091313.
32. Leung, AM, Braverman, LE, He, X, et al. (2012) Breastmilk iodine concentrations following acute dietary iodine intake. Thyroid 22, 11761180.
33. Dold, S, Baumgartner, J, Zeder, C, et al. (2016) Optimization of a new mass spectrometry Method for measurement of breast milk iodine concentrations and an assessment of the effect of analytic method and timing of within-feed sample collection on breast milk iodine concentrations. Thyroid 26, 287295.
34. Mulrine, HM, Skeaff, SA, Ferguson, EL, et al. (2010) Breast-milk iodine concentration declines over the first 6 mo postpartum in iodine-deficient women. Am J Clin Nutr 92, 849856.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

British Journal of Nutrition
  • ISSN: 0007-1145
  • EISSN: 1475-2662
  • URL: /core/journals/british-journal-of-nutrition
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Type Description Title
Supplementary materials

Huynh supplementary material
Tables S1 and S2

 Word (17 KB)
17 KB


Altmetric attention score

Full text views

Total number of HTML views: 20
Total number of PDF views: 176 *
Loading metrics...

Abstract views

Total abstract views: 590 *
Loading metrics...

* Views captured on Cambridge Core between 9th August 2017 - 21st June 2018. This data will be updated every 24 hours.