Inhibition of PG biosynthesis as the maintenance mechanism of pregnancy of hCG.

ABSTRACT

In general, when the hCG values in the serum and urine reached their first peak, the PGF2 alpha and PGF2 alpha-MUM levels dropped. The hCG fell rapidly in inverse proportion to PGF2 alpha. During late pregnancy, hCG levels increased slightly and PGF2 alpha reached a low level again. From these observations, it can be stated that both PGF2 alpha and hCG played important physiologic roles in the maintenance of pregnancy. Normal pregnancy depends on this special antagonism. This anatagonism seems to be maintained by proper concentration of both hCG and PGF2 alpha. When this antagonism is disturbed during pregnancy as described above, the tendency toward decrease of hCG and increase of PGF2 alpha manifests and hence threatened abortion or actual abortion may result.