The “Pregnancy Zone” Protein and Abortion

Abstract

The occurrence of the “pregnancy zone” protein was studied in the sera of 82 women with incomplete abortion and 272 women with apparently normal pregnancies undergoing induced abortion. In normal pregnancies the frequency of women showing the “pregnancy zone” protein increased from about 25% in gestation weeks 7–8 and to 88% in gestation weeks 17–18. In sera from women with incomplete abortion the “pregnancy zone” protein was found in a frequency of only 8–9% in gestation weeks 9–12. The results suggest that during pregnancy normal development of the ovum is necessary for the induction of the “pregnancy zone” protein. It is probable that women lacking this protein in gestation weeks 9–12 run a considerably higher risk of abortion than those who have developed this protein.