Subjects will enter a screening period of up to one month before being randomized at the Baseline Visit, which will occur on Day 1 of the subject's menstrual cycle. Each subject will then receive up to 4 weeks treatment with Gonal-f®. If adequate follicular development (assessed by transvaginal ultrasound) is achieved, the subject will proceed to administration of human chorionic gonadotropin (hCG) within 24-48hrs of last Gonal-f® injection (or according to standard site practice).