Iodine status in pregnant women in the National Children's Study and in U.S. women (15-44 years), National Health and Nutrition Examination Survey 2005-2010

Thyroid. 2013 Aug;23(8):927-37. doi: 10.1089/thy.2013.0012. Epub 2013 Jul 20.


Background: This report presents iodine data from National Health and Nutrition Examination Survey (NHANES) and from a sample of pregnant women in the National Children's Study (NCS) Vanguard Study.

Methods: Urinary iodine (UI) was measured in a one third subsample of NHANES 2005-2006 and 2009-2010 participants and in all 2007-2008 participants age 6 years and older. These measurements are representative of the general U.S. population. UI was also measured in a convenience sample of 501 pregnant women enrolled in the NCS initial Vanguard Study from seven study sites across the United States.

Results: NHANES median UI concentration in 2009-2010 (144 μg/L) was significantly lower than in 2007-2008 (164 μg/L). Non-Hispanic blacks had the lowest UI concentrations (131 μg/L) compared with non-Hispanic whites or Hispanics (147 and 148 μg/L, respectively). The median for all pregnant women in NHANES 2005-2010 was less than adequate (129 μg/L), while third trimester women had UI concentrations that were adequate (median UI 172 μg/L). Third trimester women participating in the NCS similarly had an adequate level of iodine intake, with a median UI concentration of 167 μg/L. Furthermore, NCS median UI concentrations varied by geographic location.

Conclusions: Dairy, but not salt, seafood, or grain consumption, was significantly positively associated with median UI concentration in women of childbearing age. Pregnant women in their third trimester in the NHANES 2005-2010 had adequate median UI concentrations, but pregnant women in NHANES who were in their first or second trimesters had median UI concentrations that were less than adequate. Non-Hispanic black pregnant women from both the NHANES 2005-20010 and the NCS consistently had lower UI median concentrations than non-Hispanic whites or Hispanics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Child
  • Ethnicity
  • Female
  • Humans
  • Iodine / deficiency*
  • Iodine / urine
  • Male
  • Middle Aged
  • Nutrition Surveys
  • Nutritional Status*
  • Pregnancy
  • Pregnancy Complications / epidemiology*
  • Pregnancy Complications / urine
  • Pregnancy Trimester, Second
  • Pregnancy Trimester, Third
  • United States / epidemiology


  • Iodine