It is an IVF in natural cycle or minimal ovarian stimulation in order to obtain a few oocytes that will be fertilized in the laboratory by IVF or ICSI.
Logically, since fewer oocytes can be obtained and each oocyte has the possibility of being fertilized and giving rise to a viable embryo (not all oocytes are fertilized and not all embryos evolve), the possibilities of pregnancy are less than in an IVF with a good number of oocytes (between 5 and 12 oocytes would be an ideal number).
However, in specific cases, your doctor may recommend this type of treatment, especially when there is not a good response to ovarian stimulation and even with high doses of medication.
The rate of gestation will depend largely on the patient's age. The younger the patient is, the better the chances of pregnancy.