AMNIOTIC FLUID COMPOSITION IN MALFORMATIONS OF THE FETAL CENTRAL NERVOUS SYSTEM

Abstract

Summary The results are presented of measurements of optical density at 450nm (ΔOD450), 5‐hydroxyindole acetic acid (5‐HIAA), α‐fetoprotein (AFP) and amino acids in amniotic fluid at various stages of gestation in over 60 pregnancies in which the fetus had a neural tube defect namely anencephaly and/or spina bifida. Before 20 weeks' gestation neither ΔOD450 nor 5‐HIAA levels were abnormal. AFP levels were more reliable than amino acid concentrations for the antenatal diagnosis of neural tube defects, particularly in early pregnancy. Various interpretations for these findings are discussed including the possibility that ΔOD450 and AFP levels in amniotic fluid might reflect altered maternal metabolism.