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.