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Ferritin — Pregnancy Reference Values

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Ferritin (Serum)

Ferritin reflects total body iron stores and functions as an acute-phase reactant. During pregnancy, ferritin levels normally decline due to hemodilution and increased fetal–placental iron demands.

Units Nonpregnant Female 1st Trimester 2nd Trimester 3rd Trimester
ng/mL 10 – 150 6 – 130 2 – 230 0 – 166
pmol/L 22 – 337 14 – 292 5 – 216 0 – 373
Physiology in pregnancy
  • Ferritin decreases progressively with advancing gestation.
  • Iron demand rises sharply in the second and third trimesters.
  • Ferritin may be falsely normal or elevated during inflammation.
Causes of low ferritin
  • Iron deficiency (most common)
  • Insufficient dietary iron intake
  • Increased fetal-placental iron transfer
  • Chronic blood loss (e.g., GI bleeding, pre-pregnancy menorrhagia)
  • Malabsorption (celiac disease, bariatric surgery)
  • Helicobacter pylori infection
  • Physiologic hemodilution of pregnancy
Causes of elevated ferritin
  • Acute or chronic inflammation (acute-phase reactant)
  • Infection
  • Liver disease (fatty liver, hepatitis, cholestasis)
  • Iron overload (hemochromatosis, excess supplementation)
  • Hemolysis
  • Anemia of chronic disease
Clinical interpretation & pregnancy considerations
  • Ferritin <30 ng/mL is highly suggestive of iron deficiency in pregnancy.
  • Normal or elevated ferritin does not exclude iron-restricted erythropoiesis during inflammation.
  • ACOG recommends routine anemia screening and iron supplementation when indicated.
  • Ferritin is preferred over serum iron for assessing iron stores.

References

  1. Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies. Obstet Gynecol. 2009.
  2. Bothwell TH. Iron requirements in pregnancy. Am J Clin Nutr. 2000.
  3. Milman N. Serum ferritin in pregnancy. Acta Obstet Gynecol Scand. 2006.
  4. Pavord S, et al. UK guidelines on iron deficiency in pregnancy. Br J Haematol. 2020.
  5. Kell DB, Pretorius E. Serum ferritin as an inflammatory marker. Metallomics. 2014.
  6. ACOG Practice Bulletin No. 233. Anemia in Pregnancy. Obstet Gynecol. 2021.
  7. WHO. Daily iron and folic acid supplementation in pregnant women. 2012.