Aromatase inhibition improves ovarian response to follicle-stimulating hormone in poor responders.
OBJECTIVE
To examine the use of the aromatase inhibitor letrozole with FSH for ovarian stimulation in poor responders undergoing ovarian superovulation and IUI.


METHODS
Observational cohort study as a prospective clinical trial in patients with unexplained infertility and a low response to ovarian stimulation with FSH.


METHODS
Two tertiary referral infertility clinics associated with the Reproductive Sciences Division, University of Toronto.


METHODS
Twelve patients with unexplained infertility undergoing IUI who received FSH alone in 25 prior cycles with poor response (less than three dominant follicles).


METHODS
Patients were offered letrozole, 2.5 mg/day from day 3-7 of the menstrual cycle with FSH (50-225 IU/day) starting on day 5-7. hCG (10,000 IU) was given when two leading follicles were >/=2 cm followed by IUI.


METHODS
Number of mature follicles (>1.8 cm), FSH dose, endometrial thickness, and pregnancy rate.


RESULTS
Improved response to FSH stimulation with letrozole co-treatment was evidenced by the significantly lower FSH dose associated with significantly higher number of mature follicles. During letrozole plus FSH stimulation cycles, clinical pregnancy was achieved in three cycles (21%).


CONCLUSIONS
In this preliminary report, we demonstrate a potential benefit of aromatase inhibition for improving ovarian response to FSH in poor responders.
Mitwally
Mohamed Farouk M
MF
Division of Reproductive Sciences, Department of Obstetrics and Gynecology, Samuel Lunenfeld Research Institute and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.
Casper
Robert F
RF
D047072:Aromatase Inhibitors; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D015331:Cohort Studies; D004717:Endometrium / Q000033:anatomy & histology; D004791:Enzyme Inhibitors / Q000008:administration & dosage*; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage*; D006801:Humans; D007315:Insemination, Artificial; D000077289:Letrozole; D008597:Menstrual Cycle; D009570:Nitriles / Q000008:administration & dosage; D006080:Ovarian Follicle / Q000033:anatomy & histology; D010062:Ovulation Induction / Q000379:methods; D011247:Pregnancy; D011446:Prospective Studies; D014230:Triazoles / Q000008:administration & dosage
D047072:Aromatase Inhibitors; D006063:Chorionic Gonadotropin; D004791:Enzyme Inhibitors; D009570:Nitriles; D014230:Triazoles; D004958:Estradiol; D000077289:Letrozole; D005640:Follicle Stimulating Hormone