Origin of amniocentesis-induced rises of alpha-fetoprotein concentrations in maternal serum

An elevation of alpha-fetoprotein concentration in maternal serum occurred in 7 of 65 patients (11 per cent) following amniocentesis. Analysis of the molecular heterogeneity of the alpha-fetoprotein by chromatography on concanavalin A-agarose indicated that the source of the alpha-fetoprotein was fetal serum in three patients and amniotic fluid in four patients.