Oocyte cryopreservation is now an officially sanctioned option for young women whose medical treatments may endanger their fertility.
A report by the American Society for Reproductive Medicine found that advances in egg-freezing techniques now produce rates of pregnancy and healthy babies comparable to those seen with vitro fertilization (IVF) using fresh eggs.
The society went so far as to remove the word "experimental" from the paper, in the hopes that insurance may begin to pay for egg preservation for young women who face gonadotoxic treatments, such as chemotherapy for cancer.
"We are still in the early phases of figuring out the best candidate and the best time of life to elect doing this."
"Egg freezing can be used for patients with medical indications for losing their fertility, such as cancer, impending ovarian failure, or even genetic conditions like Turner syndrome," Dr. Samantha Pfeifer, the paper’s lead author, said during a press briefing. Other indications include a failure to retrieve sufficient sperm on the day of IVF, or the cryopreservation of eggs for couples who can’t, or don’t want to, freeze embryos.
What the paper doesn’t support, however, is using oocyte cryopreservation to delay childbearing, or as any kind of an "insurance policy" for younger women against what might happen to their fertility some time in the future.
"We are aware that this has been marketed vigorously to ensure against future infertility," said Dr. Pfeifer, chair of the ASRM Practice Committee. "Conceptually this seems like a good idea, but there are no data to say that it would help many women. Only 15% of couples will ever seek treatment for infertility, and only a subset of those will attempt IVF, and only a subset of those would need to consider cryopreservation. Only women who were lucky enough to freeze eggs [during their youth], and then become infertile, would be helped by this."
The report examined data from 112 papers on oocyte cryopreservation safety and efficacy. "The largest and most compelling randomized controlled trial compared the use of fresh versus vitrified donor oocytes in 600 recipients," the report noted. "The investigators found that 92.5% of vitrified oocytes survived warming, and that there were no significant differences in fertilization rates (74% vitrified vs. 73% fresh), implantation rates (40% vs. 41%), and pregnancy rates per transfer (55.4% vs. 55.6%) between groups."
The studies’ findings also eased concerns that freezing might compromise egg quality by damaging the meiotic spindle, Dr. Pfeifer said. Advances in the technology of freezing have largely ameliorated that fear.
"Despite concerns regarding spindle abnormalities in cryopreserved oocytes, the incidence of chromosomal abnormalities in human embryos obtained from cryopreserved oocytes is no different from that of control embryos," according to the report. A recent review of more than 900 babies born from frozen eggs found no increased risk of congenital abnormalities, compared with the background population.
However, the paper noted, there are not yet any long-term developmental data on these children.
IVF with frozen oocytes is most successful with women in their 20s and early 30s – as in any other assisted reproduction technique, said coauthor Dr. Eric Widra. This truth touches directly on the issue of elective egg freezing.
"There’s an inherent conflict between the desire to freeze eggs and the need to do it," he said during the briefing. "Young women in their 20s are unlikely to have infertility, and if they do, it’s unlikely to be due to trouble with their eggs, so freezing is an insurance policy many will never need. For the older patient, freezing provides a false sense of security; technically it would be possible, but it may not give them a good chance of a live birth.
"We are still in the early phases of figuring out the best candidate and the best time of life to elect doing this," he said.
Dr. Pfeifer agreed. "We think this application should be used with caution and not be offered indiscriminately to everyone, without counseling about the options. A lot of the women interested in this are in their late 30s and early 40s, and their chance of having a live birth is not as good as younger women. These older patients must be counseled on this. This is not a technology that says, ‘Freeze your eggs so you will have more options down the road.’ The best way to conceive is with your own eggs, through natural intercourse. There are no data that support this as a social mechanism to delay childbearing."
Dr. Pfeifer and Dr. Widra said they had no relevant financial disclosures.