Pituitary down-regulation in IVF cycles: is it necessary to use strict criteria?

In a retrospective study we have reviewed the data of 570 consecutive IVF cycles in which a GnRH agonist (GnRHa) was started in the early follicular phase (long protocol). Cycles were divided in groups according to estradiol levels before HMG administration: A, < 20 pg/ml; B, 20 to 50 pg/ml; C, 51 to 100 pg/ml. Our objective was to determine if the degree of pituitary suppression had any effect on the ovarian response to stimulation by exogenous gonadotropins, and/or on the IVF outcome.

There were no significant differences in cycle cancellation rates, no. of days of stimulation and ampoules of HMG, serum estradiol after HMG, no. of oocytes retrieved and fertilization rates between groups. Pregnancy rates (19.4%, 21% and 31.8%/cycle, and 24.1%, 27.5% and 37.8% / embryo transfer, respectively) and live-birth rates (16.2%, 16.1% and 25.0%/cycle, 20.1%, 21.2% and 29.7%/embryo transfer, respectively) were also not significantly different.

The degree of pituitary suppression had no effects on either the ovarian response to gonadotropins (including HMG requirements) or the overall IVF results.