Natural cycle IVF is IVF without the use of hormonal medications to stimulate the ovary to produce multiple mature eggs. Natural cycle IVF works with the woman’s own ovulation cycle to produce mature egg(s) and the fertility doctor collects the single dominate egg that is naturally matured by the body.
It is believed the risks associated with hormonal medications, the high costs, and multiple pregnancy can be avoided when using this method as compared to conventional IVF. There is also a modified natural cycle IVF, which uses hormonal medication to stimulate the ovaries but at low doses compared to conventional IVF.
How is it done?
The woman will go through a regular menstrual cycle and will be monitored with ultrasounds and blood tests to identify the maturation of the dominant egg. The dominate egg is then collected when it reaches the appropriate size of a mature egg.
Once the mature egg is retrieved, the procedures of fertilization and implantation are similar to conventional IVF. The collected mature egg is fertilized in the laboratory and it will grow into an embryo. When the embryo reaches the stage suitable for implantation, the fertility doctor will transfer the embryo into the uterus for implantation and pregnancy will hopefully begin.
Who should use it?
All women who have normal ovulation cycles can undergo natural cycle IVF but it is best used for certain groups. These include:
- Women who have poor response to stimulation medications
- Women who have high risk of developing ovarian hyperstimulation syndrome (OHSS) or want to avoid side effects associated with the medications used in conventional IVF
- Couple with male factor subfertility
What are the advantages of natural IVF?
- Less expensive. Natural cycle IVF eliminates the costs associated with hormonal medications, which account for a significant portion of the IVF cost.
- Less side effects. By using the body’s natural ovulation processes with minimal use of medications, natural cycle IVF reduces the risks of OHSS and other complications associated with hormone drugs.
- No multiple pregnancy. In natural cycle IVF, only one dominant egg is matured and collected for fertilization. This eliminates the chance of multiple pregnancy, which carry significant risks for both the mother and the child.
- More natural. Natural cycle IVF is the closest method to natural fertilization. It offers fewer medications, fewer side effects, fewer office visits, and the IVF cycle is less time consuming, which makes it is less physical and mentally stressful for the patients.
What are the drawbacks of natural IVF?
Although there are many advantages to using natural cycle IVF if the patient is a good candidate, there are some disadvantages to take into consideration.
- Cycle cancellation. Not using hormone medications to stimulate the ovaries limits the control the fertility doctor has over the IVF cycle. This allows for many unexpected events to occur that can lead to the cancellation of the cycle. These include a premature LH surge, no ovulation, no fertilization, or embryo arrest. Natural cycle IVF can become a time-consuming and more stressful process if the cycle is cancelled and the patient needs to repeat the IVF cycle.
- No extra eggs/embryos. In a natural cycle IVF, there is only one dominant egg that is ovulated. This means there are no extra eggs or embryos to use in an event the retrieved mature egg is found to be not viable or if the patient wants to have additional children later in the future.
How does the success rate of natural cycle IVF compare to conventional IVF?
Many people claim that since the matured egg is naturally selected in natural cycle IVF, the matured egg is of higher quality than those in conventional IVF. They also believe drugs used to stimulate the ovaries may have a negative effect on the eggs collected. Studies show that there is no difference in the fertilization rates, embryo quality and implantation rates between natural IVF and conventional IVF.
In fact, a conventional IVF cycle offers a better chance to have a baby as it has extra eggs or embryos frozen in the event the first cycle does not work. Where as in natural cycle IVF, the patient will have to repeat the whole IVF cycle to obtain an egg for fertilization. Natural cycle IVF can be a good option for some women who want to limit the use of hormone medication but it is not the best choice for everyone.
Reference
Allersma T, Farquhar C, Cantineau AEP. Natural cycle in vitro fertilisation (IVF) for subfertile couples. Cochrane DB Syst Rev. 2013;8. DOI:10.1002/14651858.cd010550.pub2.
Celia, G.F, Botes, A, Gordon, J.D, DiMattina, M. Natural cycle IVF produces similar implantation rates compared with stimulated IVF. Fertil Steril. 2010; 94(4): S162.