IVF success rates do not depend on the number of eggs retrieved; rather, IVF success rates depend on the patient’s ovarian reserve, which is reflected in the number of eggs retrieved.
For immediate release
May 31, 2011 (New York, NY) – A New York IVF center warns against simplistic interpretation of a recent report on IVF pregnancy rates, published online in the medical journal Human Reproduction. The paper1 reported that maximal birth rates were achieved when 15 to 20 oocytes (eggs) were retrieved in an IVF cycle. A press release2 by the European Society for Human Reproduction and Embryology (ESHRE), which publishes the journal, summarized the study as demonstrating that “15 [eggs] is the perfect number” to strive for in every IVF cycle, and many media outlets have followed. However, according to the fertility researchers at Center for Human Reproduction (CHR) in New York, NY, this conclusion is an oversimplification of reported data.
“Assuming that patients receive reasonable ovarian stimulation for IVF,” explains Norbert Gleicher, MD, Medical Director of CHR, “the number of retrieved eggs is only a reflection of the patients’ ovarian reserve.” Ovarian reserve is a medical term that describes a woman’s current level of ovarian function. The study, showing that live birth rates plateaued between 15 and 20 eggs, only demonstrates that retrieval of 15 to 20 eggs reflects the best ovarian reserve at all ages.
According to research at CHR, ovarian reserve is also reflected in anti-M-llerian hormone (AMH) levels. In a paper3 published in the medical journal Fertility & Sterility, CHR’s IVF specialists reported last year that AMH above 1.05 ng/mL offers best live birth chances at all ages. The Human Reproduction study confirms the previous CHR finding that threshold levels of ovarian reserve, offering best IVF live birth rates, remains constant at all ages.
“Technically, ovaries cannot be stimulated toward production of a specific number of eggs,” adds David H. Barad, MD, Clinical Director of IVF at CHR. “If the number of eggs, instead of ovarian reserve, were the true determinant of live birth chances, we could simply stop retrieving eggs when we reach that specified number. This, however, would only increase risks to patients. Perfect oocyte numbers, therefore, cannot really be acted upon.”
Dr. Gleicher also warns that patients should not be misled into believing that every patient undergoing IVF can or should be stimulated toward the production of 15 to 20 eggs. Very few women above age 40, for example, can ever reach this range, even with maximal ovarian stimulation. Young women with polycystic ovary syndrome (PCOS), on the other hand, will often exceed this range, even with the mildest stimulation. “It is not the number of eggs we worry about,” says Dr. Gleicher. “It’s the patient’s ovarian reserve!”
1Sunkara et al., Association between the number of eggs and live birth in IVF treatment: an analysis of 400,135 treatment cycles
3Gleicher et al., Anti-M-llerian hormone (AMH) defines, independent of age, low versus good live-birth chances in women with severely diminished ovarian reserve. Fertil Steril 2010;94:2824-7
CHR is a leading infertility center in New York City, with world-wide patient clientele, well recognized for its extensive clinical research program, which over the years contributed a number of major breakthrough to the IVF process. Dr. Gleicher is available for additional comments.