Consequences on gonadotrophin secretion of an early discontinuation of gonadotrophin-releasing hormone agonist administration in short-term protocol for in-vitro fertilization

Administration of gonadotrophin-releasing hormone (GnRHa) agonists, used in IVF short-term protocols to initiate follicular recruitment, may be restri cted to the early follicular phase without any further risk of LH surge. Ho wever, consequences of an early discontinuation upon residual endogenous go nadotrophin secretion are still unknown. Here, the effects of early cessati on of GnRH agonist upon gonadotrophin secretion and ovarian parameters of I VF cycles were investigated. A total of 230 normo-ovulatory women were pros pectively allocated to one of the two regimens: decapeptyl-GnRH (100 mu g) was daily injected either from day 1 to the triggering of ovulation (group 1) or for the first 7 days (group 2). Exogenous gonadotrophins (150 IU) wer e administered on day 4 and 5 with a subsequent adjustment. Detections of f ree a subunit and dimeric LH were performed by highly specific 'two site' m onoclonal immunoradiometric assays. The results show that early discontinua tion of GnRH agonist administration was associated with a sharp decrease in both plasma free a subunit and dimeric LH concentrations while plasma oest radiol response to exogenous gonadotrophins was reduced. Other ovarian para meters and pregnancy rate were unchanged. These data indicate that endogeno us LH secretion is maintained by a daily administration of GnRH agonist and may contribute to the final follicular maturation.