Non protein bound iron concentrations in amniotic fluid

Clin Biochem. 2005 Jul;38(7):674-7. doi: 10.1016/j.clinbiochem.2005.03.010.


Objectives: To investigate whether amniotic fluid concentrations of non protein bound iron (NPBI) vary with growth in healthy fetuses and also offer a reference curve in the second trimester of pregnancy.

Design and methods: Amniotic fluid concentrations of NPBI were measured by HPLC in 118 women with physiological singleton pregnancies, who underwent amniocentesis for fetal karyotype between weeks 15 and 18 of gestation.

Results: NPBI increased progressively from weeks 14--15 to weeks 15--16, peaking at 17--18 weeks of gestation. NPBI values regressed positively with gestational age (GA). Multiple linear regression analysis between NPBI, as dependent variable, and various fetal parameters, as independent variables, showed a statistically significant regression coefficient with GA, bi-parietal diameter and transverse cerebellar diameter.

Conclusions: The present data constitutes the first quantification of NPBI concentrations in amniotic fluid under physiological conditions. Correlations with GA and ultrasound fetal biometry suggest that NPBI may play a role in fetal growth.

MeSH terms

  • Adult
  • Amniotic Fluid / chemistry*
  • Chromatography, High Pressure Liquid
  • Female
  • Humans
  • Iron / analysis*
  • Iron / chemistry
  • Nitrilotriacetic Acid / chemistry
  • Pregnancy
  • Pregnancy Trimester, Second / physiology
  • alpha-Fetoproteins / analysis


  • alpha-Fetoproteins
  • Iron
  • Nitrilotriacetic Acid