[Natural cycle IVF (nIVF) in women with implantation failure]

Since the introduction of IVF treatments, natural cycle IVF (nIVF) has been largely replaced by IVF with ovarian stimulation to obtain multiple oocytes. Failure to anticipate the retrieval of more than two oocytes often results in cancellation of the cycle. However, nIVF has several advantages. It is associated with a close to zero multiple pregnancy rate, and a zero risk of ovarian hyperstimulation syndrome. Per cycle, nIVF is less time consuming, physically and emotionally less demanding for patients, and cheaper than stimulated IVF, but also less effective. GnRH antagonists have improved the outcome of nIVF cycles. They avoid unexpected ovulation and frequent cancellations. In selected cases, especially in women with implantation failure or with poor ovarian response, favorable results can be obtained from nIVF cycles, despite the replacement of a single embryo. Poor results are obtained in women over 38 years.