THE PREGNANCY ZONE PROTEIN RESPONSE DURING GESTATION - A METABOLIC CHALLENGE

Prospective studies of pregnant women were performed to compare indivi dual variations in the plasma concentration of sex hormone binding glo bulin (SHBG) and pregnancy zone protein (PZP) during pregnancy, and to elucidate the degree of co-variation between these oestrogen sensitiv e proteins during gestation. The plasma concentration of SHBG manifest ed continuous increase reaching a 12-fold peak at delivery. The increa se of the protease inhibitor PZP paralleled that of SHBG reaching a pe ak with a 25-fold increase by the beginning of the third trimester. Th en it started to decline, while that of SHBG continued to increase. Th e synthesis of the protease inhibitor may also continue to increase du ring late gestation but its elimination from the circulation may be ac celerated when the syncytiotrophablastic area in contact with the mate rnal blood approaches its maximum. The unusually wide individual varia tion of PZP concentrations in nonpregnant women was confirmed. However , the individual levels increased proportionally during the progress o f pregnancy, and we may speak of low, medium and high reactors for PZP . One initial conclusion to be drawn from the present findings is that the value of the plasma PZP concentration can only be interpreted fro m a pathophysiologic point of view if the patient's baseline level is known.