Pregnancy specific β1 glycoprotein (SP1) is a specific protein which is produced by syncytial cells in placental, its molecular wightis 90, 000～110, 000Daldon, 29％ of glycomolecular, 30 hours of half life. SP1 was 97. 4％ in pregnant women of 6-8 weeks, SP1 was determinated in 100％ pregnant women at late peroid, but it was not in the normal non-pregnant women and males.The human placenta is a multihormonal endocrine organ that produces hormones, enzymes, and other molecules that support fetal survival and development.

Pregnancy-specific beta-1-glycoprotein (PSBG, PSG) is a major product of the syncytiotrophoblast, reaching concentrations of 100 to 290 mg/l at term in the serum of pregnant women (Horne et al., 1976). PSG is a member of the immunoglobulin (Ig) superfamily .