Embryo chromosome studies show high rates of abnormalities, above 50%, but most embryos studied before this study were from patients 35 and older.

In a recent study, Researchers from Reprogenetics (West San Francisco, CA), Reproductive Specialty Medical Center (Newport Beach, CA); Zouves Fertility Center (Daly City, CA) and IVF Labs (Encino, CA) evaluated the rate of chromosome abnormalities in embryos from young egg donors, and compared the range of chromosome abnormality rates between donors and non-egg donor cycles, both undergoing preimplantation genetic diagnosis (PGD) for infertility . On average, only 43 % of the embryos were chromosomally normal, although that was still significantly higher than the rate of normal embryos in the non-egg donor group, which were 34% (age group 18-34) and 21% (age group 40-45). There was considerable variation between donor cycles, with almost one-third of them having less than 30% normal embryos. Also, within donors and recipients repeating several in vitro fertilization (IVF) cycles with PGD, only 29-56% of the second PGD cycles had similar rates of normal embryos than the first cycle, while in the comparison group it was 64%. The results can explain why some egg donors are successful whereas others are not, and may also show that a policy of PGD for first time egg donors is appropriate and indicated.