The effect of human chorionic gonadotropin and estradiol-17β on the maintenance of the human corpus luteum of early pregnancy

Abstract

The effect of exogenous human chorionic gonadotropin (HCG) and estradiol valerate (EV) on the maintenance of the corpus luteum of early pregnancy, assessed by serial estimations of serum progesterone and 17α-hydroxyprogesterone (17-OHP), was studied in 35 subjects following therapeutic termination of pregnancy by suction curettage before the tenth week of gestation. Continuous intravenous infusion of 50,000 International Units (I.U.) of HCG for 24 hours following termination of pregnancy delayed the decline of serum HCG levels, and 17-OHP levels were maintained at preoperative levels for the 24 hours of the infusion. Single intramuscular injections of 5,000 or 20,000 I.U. of HCG were ineffective. Administration of 25 mg. of EV intramuscularly immediately following therapeutic termination of pregnancy slightly retarded the decline of serum 17-OHP levels. The same treatment when administered in combination with the intravenous infusion of 50,000 I.U. of HCG completely prevented the ability of HCG to maintain serum levels of 17-OHP. These findings suggest an antagonism between estradiol and HCG in maintenance of the human corpus luteum during early pregnancy.