[Revisiting the role of LH in follicular development]

During the last decade, two pivotal events widened the gap between the hormonal dynamics of ovarian stimulation and that of the menstrual cycle. First, the profound and routine suppression of endogenous gonadotropins by GnRH analogues used in ovarian stimulation pressed us to recreate the hormonal environment necessary for adequate follicular maturation and steroidogenesis. Second, drugs with reduced or null LH activity became available, based on the hypothesis that FSH action was sufficient to follicular development and maturation irrespective of residual endogenous gonadotropin levels. Today, there is a renewed interest in the possible role of LH on follicular development, in an effort to mimic the hormonal events of the menstrual cycle to optimize ovarian stimulation outcome.