Effect of treatment with gonadotropin-releasing hormone analogues on pregnancy outcome in the baboon.

The effect of a gonadotropin-releasing hormone (GnRH) agonist, Zoladex (Imperial Chemical Industries, PLC, London, England), and an antagonist, Organon 30276 (Organon, Oss, Holland), on the outcome of pregnancies when administered just after implantation was examined. The antagonist, Organon 30276, was administered continuously from days 14 through 21, and the agonist, Zoladex, was injected as long-acting pellets on day 14 after conception to pregnant baboons. Maternal baboon chorionic gonadotropin and progesterone levels and sonographic measurement were made before, during, and after treatment and throughout pregnancy of control and treated animals. Two pregnant animals were treated with 3.6 mg of Zoladex; one aborted and one had a stillbirth. Another four pregnant baboons were treated with 7.2 mg of Zoladex; two aborted, one had a premature with a low-birthweight infant, and one had a normal liveborn. Organon 30276, at 50 mg, was administered to three pregnant baboons and resulted in one stillbirth, one neonatal death, and one normal liveborn. The two pregnant baboons treated with 100 mg Organon 30276 both aborted. Therefore, treatment with these GnRH analogues in very early baboon pregnancy could adversely affect the outcome of pregnancy. Thus attention should be paid to the possible presence of early pregnancy at the time of GnRH analogue therapy, which might adversely affect the outcome of the pregnancy.