Is there a place for natural or modified natural cycles?

Without stimulation, IVF in natural or modified natural cycles (IVF-NAT) offers an interesting alternative to controlled ovarian hyperstimulation for some patients. This protocol may be proposed to patients suffering from altered ovarian status with encouraging results. The second indication might be patients presenting with repeated implantation failure. IVF-NAT allows possible adverse effects of controlled ovarian hyperstimulation on the endometrium to be avoided. Results of clinical pregnancy rate per oocyte retrieval for altered ovarian status and implantation failure are 15.4 and 16.6%, respectively, and 25.5 and 26.3%, respectively, over three cumulative cycles. This treatment is less expensive and patient friendly.