Aromatase Inhibition Reduces the Dose of Gonadotropin Required for Controlled Ovarian Hyperstimulation

M.F. Mitwally, Mitwally MF, Mohamed F M Mitwally, Casper RF, Robert F. Casper
Journal of the Society for Gynecologic Investigation · 2004 · vol. 11(6) , pp. 406–415 · doi:10.1016/j.jsgi.2004.03.006 · PMID:15350255 · W2079266189
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This study investigated how aromatase inhibitors affect the gonadotropin dose needed for controlled ovarian hyperstimulation in women undergoing fertility treatment.

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Abstract

ObjectiveTo compare the use of the aromatase inhibitor, letrozole, in conjunction with follicle-stimulating hormone (FSH) injection, and FSH alone for controlled ovarian hyperstimulation (COH) in patients with polycystic ovarian syndrome (PCOS) or ovulatory infertility.MethodsThis nonrandomized study included two study groups: 26 patients with PCOS and 63 with ovulatory infertility (unexplained infertility [41 patients], male factor infertility [17 patients], and endometriosis [5 patients]), who received letrozole in addition to FSH; and two control groups: 46 PCOS patients and 308 with ovulatory infertility (unexplained infertility [250 patients], male factor infertility [42 patients], and endometriosis [16 patients], who received FSH only. All patients had intrauterine insemination (IUI). Main outcome measures included dose of FSH used per cycle, number of preovulatory follicles greater than 16 mm in diameter, cancellation rate, and pregnancy rate.ResultsThe FSH dose required for ovarian stimulation was significantly lower when letrozole was used in both study groups compared to the control groups without a significant difference in number of follicles greater than 16 mm. IUI cancellation rate was significantly lower with letrozole treatment in PCOS patients. In women with PCOS, clinical pregnancy rate per completed IUI cycle was 26.5% in the letrozole plus FSH group versus 18.5% in the FSH-only group. In ovulatory infertility patients, the pregnancy rate was similar in both study and control groups (11%).ConclusionWe believe that inhibition of estrogen synthesis by aromatase inhibition will release the estrogenic negative feedback, resulting in an increase in endogenous FSH secretion. Moreover, by inhibiting conversion of androgens into estrogens, accumulating androgens may increase follicular sensitivity to FSH. Such a protocol has the potential to lower FSH treatment cost and may improve response for low responders who require high FSH doses during ovarian stimulation.

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MeSH descriptors

Aromatase Inhibitors Follicle Stimulating Hormone Follicle Stimulating Hormone Nitriles Ovulation Induction Polycystic Ovary Syndrome Triazoles Adult Aromatase Inhibitors Female Follicle Stimulating Hormone Follicle Stimulating Hormone Humans Infertility, Female Infertility, Female Letrozole Nitriles Ovarian Follicle Ovarian Follicle Ovarian Follicle

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