New Medical Guidelines for Egg Freezing Affect Future Pregnancies
It has a non-memorable technical name – oocyte cryopreservation, or egg freezing – and there are new clinics springing up worldwide offering their services. One ad reads, “Freeze your eggs – The nation’s egg freezing leader.” They’re not talking about chicken eggs. Freezing a woman’s eggs until the time when she is ready for pregnancy (or several other fertility scenarios) used to be science fiction fodder, now it’s going mainstream. According to the American Society for Reproductive Medicine (ASRM), which published new guidelines for the controversial practice on October 22, 2012, the growth of egg freezing clinics prompted the effort to set medical and ethical standards.
Cryopreservation, freezing of sperm or eggs, is hardly new. The first sperm were frozen and thawed in 1953, eggs and embryos in the 1980’s. Specialists consider the techniques ‘routine.’ It’s estimated that between 300,000 and 500,000 successful babies were born from frozen eggs since 1980. The technique is a solution for women who because of cancer, injury or other illness cannot bear children for a lengthy period, but wish to have children after they recover.
In the official medical community, such as the ASRM until now, and in most people’s minds, freezing eggs for future use is ‘experimental.’ Many of the egg freezing cases took place only in clinical trials (at least in the U.S.) and with an institutional review board (an IRB) acting as overseer. Considering that the total egg freezing process costs around $20,000, plus several hundred dollars a year for storage, this is a profit-center for participating clinics.
To no surprise, many clinics offer the service outside the clinical trials and review board purview.The four large clinical trials of oocyte cryopreservation conducted in the United States had generally successful results (babies born alive), roughly at the same rate of success, 80%-90%, as assisted reproduction with ‘fresh’ oocytes.
There are now two main techniques. They both begin with egg extraction in much the same way as in vitro fertilization. The woman begins with a regimen of hormones to stimulate the ovaries to produce multiple ripe eggs. When the eggs are mature, drugs trigger ovulation and the eggs are removed from the body with a brief procedure using a thin aspiration needle guided by ultrasound. The egg is then dehydrated to reduce the formation of ice crystals and the water replaced with cryoprotectants (a form of anti-freeze). This is where the procedures diverge. In one, the egg slowly cools until it is frozen. In the other, flash freezing takes only a few minutes, a process of vitrification (literally, turned to stone). Flash freezing requires somewhat more anti-freeze in the egg, but result is free of ice crystals and solid like glass. It has had a somewhat higher success rate than slow freezing and is now the preferred method.
When the cryo-egg is unfrozen, the shell of the egg hardens, making it unfit for natural fertilization. Instead, an embryologist injects the sperm directly into the egg – the same technique used for in vitro fertilization. The mother then receives a uterus implant of the fertilized egg.
Although the entire procedure seems somewhat brutal, it works. Successful babies are born on a routine basis. At least it works as far as we know. The overriding problem with egg freezing is its relative short history. As yet, there is no data about the long-term developmental effects on children born by this method.
Although recent studies indicate that frozen egg children do not seem to develop an unusual rate of serious genetic (or other) disorders, there are also studies that show some IVF and frozen egg babies are at greater risk for Angleman syndrome, a neurological condition. This syndrome appears to be caused by epigenetic changes, changes to the genes in the chromosome that occur during cell division (normal cell growth). It is possible that freezing the eggs contributes to the epigenetic changes.
Of course, time will tell. For the future, many women are in the position of wishing to preserve their remaining eggs as they get older – in fact, preserve them past their reproductive years. The implication for many women in this situation is the use of surrogate mothers. This aspect of oocyte cryopreservation has potentially large implications for society, where the number and complexity of fertilization scenarios quickly begins to resemble the melodrama of television shows such as Private Practice.
Ethical, religious and medical issues have a way of coming together around the practice of fertilization and childbirth. The technology is rapidly improving and the procedures are becoming commonplace; meanwhile the long-term effects are still unknown as are the implications for society. What can be said right now is that freezing eggs and in vitro fertilization works; it is becoming an industry because so many women (and couples) will pay to do it. Whatever the objections, this seems like a long-term experiment we’re bound to have.