Human pregnancy-associated plasma proteins during the postpartum period

The plasma levels of four pregnancy-associated plasma proteins (PAPP's) and pregnancy zone protein (PZP) were studied in women after delivery of a single viable infant by gel immunodiffussion methods. Data from 89 random samples and 85 serial specimens from five women revealed that both PAPP-B and HPL (PAPP-D) disappeared within a day after delivery. PAPP-A showed a rapid drop in the first 2 or 3 days post partum and became nondetectable in 4 to 6 weeks, with a half-life of 3 to 4 days. PAPP-C had a sharp decrease by the second postpartum day and was not detected 3 to 4 weeks later, with a half-life of 1 to 2 days. None of the PAPP's was detected again during the rest of the 14 postpartum weeks studied. In contrast, the PZP showed a much slower decrease or even a temporary increase during the first 2 weeks post partum; it remained readily detectable over the entire 14 weeks studied.