Frozen eggs which are usually used for invitro-fertilization could actually produce less live births compared to using fresh eggs, a research suggests, although the difference between the two is negligible.

A research conducted by a team of experts from the Center for Human Reproduction in New York looked into data from 380 fertility centers across the country, which takes charge of 92 percent of all IVF cycles. The data was from 2013, the year that the American Society for Reproductive Medicine ruled that oocyte cryopreservation, or freezing donated eggs, was no longer an experimental procedure.

Likewise, 2013 data also shows that 20 percent of the 11,148 IVF cycles were done that year used preserved eggs. During that period, women with implanted embryos who used fresh eggs yielded 49.6 percent of live birth. Those who use frozen eggs yielded less (only 43.2 percent ). Considering the number of embryos received, the live birth rate for fresh eggs was higher, at 56.1 percent, while those who utilized frozen eggs were only at 47.1 percent.

The data of the research was only exclusive to donor eggs. According to Stephen Faller of, "most women who freeze their eggs are not as young or healthy as those who are screened for donation, so pregnancy rates likely are affected by their specific health situation."

Researchers, however, revealed that "reasons for lower live birth rates with use of cryopreserved oocytes" still remains to be established.

"One possible explanation is less opportunity for proper embryo selection due to smaller starting numbers of oocytes, leading to fewer embryos available for transfer. Alternatively, oocyte quality may be negatively affected by cryopreservation and thawing," wrote the researchers in the journal American Medical Situation.

"Egg quality may be negatively affected by cryopreservation and thawing," lead author Dr. Vitaly Kushnir mentioned in an interview with Telegraph.

"Women who are considering selectively freezing their own eggs for fertility preservation should be counselled that pregnancy chances with frozen eggs maybe be somewhat lower than fresh," Dr. Kushnir continued.