Natural IVF What is natural IVF? In vitro fertilization (IVF) with Natural Cycle focuses on the egg that has been spontaneously selected that month. Its fertilization is performed under in vitro culture conditions in the laboratory with sperm that may have been isolated from a sperm sample (from the spouse or an anonymous donor) or obtained through a testicular biopsy. View more This type of treatment is usually used in patients who have had a low performance in previous cycles of IVF with stimulation and who rule out egg donation or in patients in whom ovarian stimulation is ruled out because they suffer from a disease that could be worsened by an increase in oestrogen levels or because they do not wish to undergo it. The expected gestation rate of this type of cycle is very variable according to the age, ovary reserve, masculine factor and base pathology.