Prognostic value of the pregnancy zone protein during early pregnancy in spontaneous abortion.

The concentration of pregnancy zone (PZ) protein in maternal serum during early normal pregnancy was followed in a prospective study of 261 pregnant women. A marked increase which followed an exponential function was found and a theoretic onset of induction at the time for implantation was calculated. Women with a later spontaneous abortion had low values. The prognostic relevance of PZ determinations was studied and values from women who later had a spontaneous abortion were compared to those from normal pregnancies. The prognostic value of PZ protein was compared to that of hCG and progesterone. PZ and hCG assays had the same prognostic accuracy concerning the outcome of pregnancy while determinations of progesterone were less valuable.