Studies on Pregnancy‐associated Plasma Protein a in the Third Trimester of Pregnancy

Abstract

Summary The plasma concentration of pregnancy‐associated plasma protein A (PAPP‐A) was measured in 34 women during the last 10 weeks of pregnancy. From 30 to 36 weeks the concentration of this protein increased steadily. Thereafter the concentration of PAPP‐A rose more steeply, the highest amounts being found in early labour. The concentration of PAPP‐A in peripheral venous blood and in the uterine vein was much the same. It was less in the retroplacental blood and a great deal less in the peritoneal fluid. The day‐to‐day variation was small; the coefficient of variation at 38 weeks was only 7.3 per cent. After delivery, the concentration of PAPP‐A fell more slowly than other placental proteins and steroids, the average half‐life being 51 hours. Although there is no doubt that PAPP‐A is a product of the syncytiotrophoblast, our findings suggest that it is not simply secreted by the chorionic villi directly into the intervillous space but makes its way into the maternal circulation by a more circuitous route.

Placental corticotrophin-releasing hormone: Activator of the pituitary–adrenal axis in human pregnancy?

“…The rate of rise of CRH (pg/ml) per week was associated with weight gain (Y 0.36, P<0.05) but with no other obstetric variable (Wolfe et al 1988~). The sharp rise in maternal plasma CRH levels up to term is similar to that found for pregnancy-associated plasma protein A (PAPP-A) (Smith et al 1979) but is unlike most other placental proteins, which plateau in the late third trimester (Bischof et al 1982). The small but significant rise in CRH levels between the end of pregnancy and labour is of interest with regard to the possible role of CRH in the process of parturition.…”

The relationship between first-trimester pregnancy-associated plasma protein-A levels and intrapartum fetal distress development

“…The serum PAPP-A level starts to increase during the first trimester, doubling every 3 to 4 days. The rate of increase is gradual until week 36, after which it accelerates, and the maximum serum PAPP-A levels are reached at term (2). It is thought that PAPP-A released from trophoblastic tissues at abnormal levels early during gestation affects fetal growth negatively by impairing trophoblastic invasion of the decidua, causing abnormal placentation and other pregnancy complications (3).…”

Pulsatile secretion of pregnancy‐associated plasma protein‐A (PAPP‐A) in non‐pregnant women

“…How can a protein with an apparent half life of 52h (Smith et al 1979) show such sudden changes in circulating concentrations? How can a protein with an apparent half life of 52h (Smith et al 1979) show such sudden changes in circulating concentrations?…”