The effect of LHRH analogs on pregnancy in the baboon

Thirty-three baboons were maintained throughout their peri-ovulatory period in group enclosures with fertile males. They received treatment on days 14-19 of presumed pregnancy with either twice daily injection of 50 micrograms of an LHRH agonist or of 2 mg of an LHRH antagonist. Three pregnancies from 14 cycles were maintained in each of the treatment groups as compared to 5 of 14 in controls. Four abortions were noted but as 1 occurred in a control group the response could not be attributed to treatment. The agonist had no apparent effect on urinary progestins in nonpregnant animals but both analogs did cause a transient decline in pregnant animals. Results indicated that LHRH analogs are not suitable agents for early pregnancy termination under the present treatment regimen.