[Are mild ovarian stimulations for IVF-ET a significant progress in assisted reproductive technologies?]

Growing evidence indicates that mild ovarian stimulation for in vitro-fertilization-embryo transfer may be an interesting approach to reduce the incidence and severity of complications, the number of treatment days, cost, patient discomfort and number of patient drop-outs. However, the heterogeneity of FSH-sensitive follicles, presumably requires multiple follicular growth to improve oocyte-embryo selection. In addition, whether the acceptability probably is similar between standard ovarian stimulation and mild stimulation, per-treatment pregnancy rates with conventional stimulation is superior to mild stimulation in unselected populations. Hence, some specific indications tend to emerge such as alterations of the ovarian follicular reserve in women of less than 38 years, bad embryo qualities and implantation failure after conventional stimulation, patients with previous history of hyperstimulation syndrome or contraindications to hyperoestrogenia (estrogeno-related cancers and thromboembolic diseases). However, no randomized trials have ever been performed to compare the results of mild versus conventional stimulation in young patients and good responders. Therefore, there is insufficient scientific evidence to shift from standard stimulation to mild stimulation for all patients. Cultural standards have to be considered in the choice of the type of stimulation.