NaturaI IVF cycle
It is an IVF cycle without using hormonal medication to stimulate the ovaries. This is how assisted reproduction began in the 70s when there was not any knowledge of stimulant medication. We only monitor the natural growth of a follicle in the ovary and when it reaches a sufficient size, we perform its follicular aspiration – egg retrieval. We should obtain one egg and fertilize it, and then transfer the embryo into the uterus.
The natural IVF cycle is a choice of women who for various reasons do not want to undergo hormone stimulation. Furthermore, it is chosen by the patients who are no longer eligible to have the IVF cycle covered by the insurance; this process is generally cheaper. The natural cycle is attractive for the patients who are poorly responsive to stimulation (low responders). Despite hormonal stimulation with high doses, they have at maximum of 1-2 follicles growing in the ovaries as well as in their natural (native) cycle.
The success rate of natural IVF cycles is generally lower for several reasons. In many cases, such treatment is undergone by women who did not become pregnant in the standard IVF cycle with hormone stimulation, or by above mentioned low responders. It is therefore a selected group of patients who generally have a lower chance of becoming pregnant. From experience, we actually know that without hormonal stimulation where the processes of oocyte maturation are precisely controlled, there is a greater risk that the egg is aspirated at the wrong time and so we obtain it immature or we do not obtain it at all. In hormonal stimulation, we have more eggs to choose from. If any egg does not get fertilized or if the embryo does not further develop, there is still a chance that we will have a "good" embryo for embryotransfer. If we have only one egg, there is a greater risk that the embryotransfer does not take place at all. The chance of becoming pregnant is similar if the embryotransfer is performed. Therefore, more natural cycles are needed to become pregnant.
Sometimes we choose the IVF cycle with minimal stimulation, when we administer lower amount of stimulants than usual. Subsequently, we expect at maximum 4 follicles to grow and we have the cycle “under the control”.
The natural IVF cycle as well as the cycle with minimal stimulation is commonly offered in our Centre.