The role of aromatase inhibitors in ameliorating deleterious effects of ovarian stimulation on outcome of infertility treatment

Abstract

Clinical utilization of ovulation stimulation to facilitate the ability of a couple to conceive has not only provided a valuable therapeutic approach, but has also yielded extensive information on the physiology of ovarian follicular recruitment, endometrial receptivity and early embryo competency. One of the consequences of the use of fertility enhancing agents for ovarian stimulation has been the creation of a hyperestrogenic state, which may influence each of these parameters. Use of aromatase inhibitors reduces hyperestrogenism inevitably attained during ovarian stimulation. In addition, the adjunct use of aromatase inhibitors during ovarian stimulation reduces amount of gonadotropins required for optimum stimulation. The unique approach of reducing hyperestrogenism, as well as lowering amount of gonadotropins without affecting the number of mature ovarian follicles is an exciting strategy that could result in improvement in the treatment outcome by ameliorating the deleterious effects of the ovarian stimulation on follicular development, endometrial receptivity, as well as oocyte and embryo quality. PART ONE IntroductionCurrent epidemiological evidence suggests that 15% of couples will experience infertility. Background prevalence rates now appear to be reasonably stable, but there is evidence of an increase in the rate of referrals for medical help [1,2]. Farley and Belsey, 1988 [3], have reported estimates of the prevalence (percentage) of primary infertility by region and country.

Use of letrozole in assisted reproduction: a systematic review and meta-analysis

“…According to lower estradiol levels associated with the use of AIs, these agents may be indicated to reduce the risk for severe ovarian hyperstimulation syndrome. It has been argued that low estradiol concentrations may be effective to suppress premature LH surge ( Mitwally et al ., 2005b ). Secondarily, stimulation of the endogenous production of gonadotrophins through negative feedback mechanisms reduces the use of exogenous gonadotrophins and, consequently, the cost of an IVF treatment cycle ( Goswami et al ., 2004 ).…”

Effects of Panax ginseng, zearalenol, and estradiol on sperm function

“…Estradiol (E 2 ) is found in the reproductive tract fluids of males and females. E 2 seems to be required for normal germ cell development; however, exceeding this level can cause dysfunction [6] , [7] . Nonfertile men had higher concentrations of E 2 , with 53% having seminal estradiol concentrations above the 90 th percentile value for fertile men [8] .…”

Comparison of GnRh Agonist Microdose Flare Up and GnRh Antagonist/Letrozole in Treatment of Poor Responder Patients in Intra Cytoplaspic Sperm Injection: Randomized Clinical Trial

“…Letrozole is a special non-steroidal Aromatase inhibitor which was first used in breast cancer in mono-pose women for suppression of estrogen products and today it is applied as the first line of induction in PCO women (Polycystic ovary) ( Yarali et al, 2009 ). It seems that Aromatase inhibitors (Letrozole) cause reduction in the need for Gonadotropins during IVF (in vitro fertilization) and ICSI (intra cytoplasmic sperm injection) cycles by reduction in estrogen that this issue causes reduction in patient costs besides reducing Gonadotropins’ side effects ( Mitwally et al, 2005 ). Mitwally et al indicated that Aromatase inhibitors cause improvement in ovary’s respond to FSH in poor responder patients ( Goswami et al, 2004 ).…”