Pretreatment with a gonadotropin-releasing hormone agonist and an aromatase inhibitor may improve outcomes in in vitro fertilization cycles of women with stage I-II endometriosis

OBJECTIVE: To determine whether 2 months of pretreatment with 5 mg of letrozole daily plus leuprolide acetate at 3.75 mg monthly in women with laparoscopically confirmed American Society of Reproductive Medicine stage I-II endometriosis improves in vitro fertilization (IVF) outcomes. DESIGN: Prospective cohort study. SETTING: University-affiliated tertiary hospital. PATIENT(S): Women with laparoscopically confirmed endometriosis treated in the period from 2012 to 2016. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Primary outcomes: clinical pregnancy and live-birth rate; secondary outcomes: stimulation parameters and pregnancy. RESULT(S): A total of 68 patients were included in the final analysis. Thirty-six women received a gonadotropin-releasing hormone (GnRH) agonist and an aromatase inhibitor (AI), and 32 women received a GnRH agonist alone. The women did not differ in mean age, antral follicle count, basal serum level of follicle-stimulating hormone, or previous pregnancies. The stimulation parameters were similar between both groups: gonadotropin dose, number of collected oocytes, number of blastocysts. All women underwent a single blastocyst transfer. The grade of embryos transferred did not differ. Clinical pregnancy (24 [66.7%] vs. 13 [40.6%]) and live-birth (22 [61.1%] vs 10 [31.3%]) rates improved with aromatase inhibitor added to the GnRH agonist treatment versus a GnRH agonist alone. CONCLUSION(S): In this study, we present the first comparison in the medical literature comparing IVF outcomes in women with minimal and mild endometriosis pretreated with a GnRH agonist with or without an AI. This prospective cohort study suggests that combining these two treatment modalities which work at different sites may improve pregnancy outcomes with IVF treatment.