Individuals undergoing In Vitro Fertilization must undergo controlled ovarian hyperstimulation (COH) to produce enough quality eggs for fertility treatment. Ovarian follicular responsiveness to COH with gonadotropins is extremely variable between patients and even from cycle to cycle for the same patient. Achieving an ideal follicular response is critical to the success of assisted reproduction treatment (ART). Patients have been classified as 'poor', 'normal' or 'high' responders, which dictate the amount of gonadotropins that they receive. It is still important to develop treatments with high efficacy, lower multiple birth rates, and a lower complication rate for each of these groups. In an era of evidence-based medicine and with special emphasis on reducing IVF risks (mainly OHSS and pregnancies with multiples), it is very important to find optimal and safe ovulation induction and triggering regimens for each patient population.