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Implantation rates in unstimulated IVF cycles compared favorably with those in stimulated IVF cycles in a retrospective analysis.
For couples who have difficulty conceiving, natural cycle in vitro fertilization (IVF) is a good alternative option for a wide range of patients, concluded the authors of a retrospective analysis.1
According to data reported to the Society of Assisted Reproductive Technology (SART) in 2006 and 2007, unstimulated IVF, also called natural cycle IVF, accounted for less than 1% of all IVF cycles initiated in the United States. Unstimulated IVF differs from standard, or stimulated, IVF in that unstimulated IVF does not involve the use of ovary-stimulating medications. Instead, the growth of the dominant follicle is tracked with ultrasounds and blood tests, and the egg is retrieved when the dominant follicle is deemed large enough. As with traditional IVF, the retrieved egg is then fertilized and, if an embryo is produced and continues to develop, it is transferred back to the uterus.
Unstimulated IVF is associated with less risk than traditional IVF because fewer medications are needed; thus, the risk of ovarian hyperstimulation syndrome (OHSS) is eliminated. Also, unstimulated IVF is less costly, requires fewer office visits, and results in less physical and emotional stress.2
According to SART data, a total of 795 cases of unstimulated IVF cycles were initiated in 2006 and 2007.1 The investigators reported that the success rates of unstimulated IVF were largely dependent on age. In patients younger than 35 years, the clinical pregnancy rates per cycle, retrieval, and transfer were 19.2%, 26.8%, and 35.9%, respectively. For this age group, the pregnancy rate was 19.2% and the live birth rate was 15.2% per initiated cycle.
In patients aged 35 to 42 years, the investigators found that implantation rates were statistically higher for unstimulated IVF compared with stimulated IVF. Overall, implantation rates in unstimulated IVF cycles compared favorably with those in stimulated IVF cycles, the investigators concluded.
It has been reported that unstimulated IVF is a reasonable option not only for infertile couples undergoing their initial cycle of IVF but also for women considered “poor responders” to continue the IVF process even after ovarian stimulation has repeatedly failed to produce multiple embryos.2
- Implantation rates in unstimulated IVF cycles favorably compare to stimulated IVF.
- Natural cycle IVF may be a good alternative treatment option for infertile couples.
- Unstimulated IVF accounts for less than 1% of all IVF cycles in the United States.
1. Gordon JD, Dimattina M, Reh A, et al. Utilization and success rates of unstimulated in vitro fertilization in the United States: an analysis of the Society for Assisted Reproductive Technology database. Fertil Steril. 2013 Apr 13. doi: 10.1016/j.fertnstert.2013.03.037. [Epub ahead of print.]
2. Bendikson K. Natural cycle IVF: today and tomorrow. April 14, 2010. Available at: http://uscfertility.org/blog/post/213-natural-cycle-ivf-today-and-tomorrow. Accessed July 31, 2013.