Assessment of iron status in US pregnant women from the National Health and Nutrition Examination Survey (NHANES), 1999-2006

Am J Clin Nutr. 2011 Jun;93(6):1312-20. doi: 10.3945/ajcn.110.007195. Epub 2011 Mar 23.


Background: Total body iron calculated from serum ferritin and soluble transferrin receptor concentrations allows for the evaluation of the full range of iron status.

Objective: We described the distribution of total body iron and the prevalence of iron deficiency (ID) on the basis of total body iron in US pregnant women.

Design: We examined data from the National Health and Nutrition Examination Survey (NHANES) in 1999-2006 for 1171 pregnant women.

Results: ID prevalence (±SE) in US pregnant women, which was defined as total body iron <0 mg/kg, was 18.0 ± 1.4%. Pregnant women in the first trimester had a higher mean total body iron than did pregnant women in the second or third trimesters. ID prevalence in pregnant women increased significantly with each trimester (6.9 ± 2.2%, 14.3 ± 2.1%, and 29.5 ± 2.7% in the first, second, and third trimesters, respectively). Pregnant women with parity ≥2 had the lowest mean total body iron and the highest prevalence of ID compared with values for pregnant women with parity of 0 or 1. The ID prevalence in non-Hispanic white pregnant women was significantly lower than in Mexican American or non-Hispanic black pregnant women. The mean total body iron and the prevalence of ID did not differ by educational level or by family income.

Conclusions: To our knowledge, these are the first data on total body iron distributions for a representative sample of US pregnant women. Low total body iron is more prevalent in pregnant women in the second or third trimesters, in Mexican American pregnant women, in non-Hispanic black pregnant women, and in women with parity ≥2.

MeSH terms

  • Adult
  • African Americans
  • Anemia, Iron-Deficiency / blood
  • Anemia, Iron-Deficiency / epidemiology*
  • Anemia, Iron-Deficiency / ethnology
  • Female
  • Ferritins / blood
  • Humans
  • Iron / blood
  • Iron Deficiencies*
  • Mexican Americans
  • Nutrition Assessment*
  • Nutrition Surveys
  • Nutritional Status*
  • Parity
  • Pregnancy
  • Pregnancy Trimesters
  • Prevalence
  • Receptors, Transferrin / blood
  • United States / epidemiology


  • Receptors, Transferrin
  • Ferritins
  • Iron