Studies of pregnancy-associated murine serum proteins.

A pregnancy-associated murine protein (PAMP) with alpha1 electrophoretic mobility and an estimated molecular weight of 140,000 was present in serum from pregnant and sexually mature non-pregnant females, but could not be detected in the serum of males. During pregnancy the serum concentration of alpha1-PAMP rose to a maximum in mid-pregnancy followed by a decline to preconception levels before parturition; the protein was also present in fetal and neonatal serum and in amniotic fluid at low concentrations.