A local report on iodine status of pregnant women during early gestation

Wednesday, Feb 14, 2018

The article was to report iodine status of pregnant women during early gestation at a local obstetric unit.


Tam WH, Chan RS, Chan MH, Yuen LY, Li L, Sea MM, Woo J. Moderate iodine deficiency among pregnant women in Hong Kong: revisit the problem after two decades. Hong Kong Med J. 2017;23(6):586-93.
Link to full article: http://www.hkmj.org/abstracts/v23n6/586.htm

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Summary of an Endocrine Society Clinical Practice Guideline


  • A local population survey conducted by the Centre for Food Safety during 2005 to 2007 indicated that only 5% adults had an iodine dietary intake within the safe range, but clinical and biochemical data was missing
  • Pregnant women have increased iodine requirement and iodine deficiency during early pregnancy has been shown to be associated with undesirable cognitive development in early childhood
  • The study aims to report the iodine status among local pregnant women at a local obstetric unit


  • Between July 2014 and November 2015, healthy pregnant women with no history of hyperemesis gravidarum were enrolled
  • Morning urine from ALL women was collected for measurement of iodine and creatinine levels
  • Daily dietary intake of iodine was measured  in a subgroup of women via structured interview using a standard food frequency questionnaire

Key Findings:

  • 600 pregnant women were enrolled (median of 7.0 weeks of gestation)
  • 71.5% women (429 out of 600) were iodine deficient according to the WHO definition, urinary iodine concentration (UIC) < 150 mcg/L
  • In the subgroup of women (n  = 146):
    • The median (IQR) daily dietary intake of iodine was 69.5 (47.3 – 152.4) mcg
    • Food sources of iodine:
      • Seaweeds, consumed by 76% of women, were the greatest source of iodine
      • Non-alcoholic beverages like soy milk, soup, soft drinks and water were the next most common source of iodine, contributing 21.5% of daily iodine intake
      • Only 4 out of 146 women consumed iodized salts regularly
  • At the time of enrollment, nutritional supplementation was reported by 69.0% women (414 out of 600), but only 39.4% (163 out of 414) of the supplements had iodine
  • In multivariate regression analyses, pregnant women recruited at a later gestational stage had a significantly higher UIC and were more likely to have started consuming a supplement with iodine


  • Local pregnant women are borderline iodine-deficient and have an inadequate iodine intake during early pregnancy
  • It is needed to educate the general public and to recommend women of childbearing age to have sufficient iodine intake before pregnancy


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