Natural in vitro fertilization cycles.

Although the first in vitro fertilization (IVF) baby was born after a natural IVF cycle, very soon this procedure was almost abandoned mainly because of the very high cancellation rates, and controlled pharmacological ovarian hyperstimulation became the standard treatment in IVF cycles of normoresponder patients. However, in poor-responder patients, where only very few follicles can be recruited and very few oocytes, if any, can be retrieved after controlled ovarian hyperstimulation, natural IVF cycles may offer a comparable number of follicles, reduced costs, and less discomfort for the patients. In this group of patients, natural IVF cycle is a cost-effective approach.