Placental prolactin-related proteins may play a specific role during gestation. N-Glycosylated; the glycans terminate in either N-acetyl-galactosamine (GalNAc) or N-acetyllactosamine (PubMed:17071780). Terminal GalNAc on Asn-linked glycans is greatly reduced prior to parturition while lactosamine-type N-glycans remain unaltered (PubMed:17071780). Belongs to the somatotropin/prolactin family.