[In vitro fertilization (IVF): why doing it in unstimulated cycles?].

In vitro fertilization without stimulation, in natural or semi-natural cycles ("FIV-NAT") offers an interesting alternative to controlled ovarian hyperstimulation (COH) for some patients. This protocol may be proposed to patients suffering from altered ovarian status (AOS) with encouraging results. The second indication might be patients presenting repeated implantation failure (IMF). FIV-NAT allows avoiding possible adverse effects of HOC on the endometrium. Results are respectively 15.4 and 16.6% clinical pregnancy rate per oocyte retrieval for AOS and IMF, and 25.5 and 26.3% over 3 cumulative cycles. This treatment is less expensive and patient friendly.