Temporary exposure of follicles to increased levels of androgens may augment follicular responsiveness. The present study tested whether short-term androgen priming by aromatase inhibitor and human chorionic gonadotrophin (hCG) before controlled ovarian stimulation (COS) increases the number of top-quality embryos after IVF/ICSI.

Patients were randomized to androgen priming (n = 53): anastrozole 1 mg cycle day (c.d.) 2, 3 and 4, hCG 1250 IU and cetrorelix 3 mg on c.d. 2, rFSH 150 IU from c.d. 5 following a flexible antagonist protocol; or control (n = 50): flexible antagonist protocol.

The mean (confidence interval) number of top-quality embryos was 1.08 (0.83,1.40) and 1.43 (1.12,1.81) in the priming and control group, respectively, being 32% (−7%, 89%) higher in the control compared to priming group (P = 0.120). Stimulation duration was longer in the priming group (P < 0.001). On the day of hCG administration, the proportion of c.d. 2 antral follicles reaching ≥14 mm was higher in the priming group (P = 0.014), as were serum estradiol (E₂) (P < 0.001) and E₂ per follicle ≥14 mm (P = 0.005). Pre-ovulatory follicular fluid levels of E₂ (P = 0.007) and testosterone (P = 0.014) were higher in the priming group. The number of oocytes retrieved was similar. The fertilization rate was lower in the priming group (P = 0.007). Ongoing pregnancy rates in priming and control group were 30 and 36% (P = 0.531).

Administration of aromatase inhibitor and hCG before COS for IVF/ICSI failed to improve the number of top-quality embryos. ClinicalTrials.gov Identifier is NCT00286364.