By Dr. Sasmira Lalwani, Reproductive Endocrinologist – IVF New Jersey
When you are 21 years old 90% of your eggs are normal. At age 41 90% of your eggs are abnormal making the dream of having a child often impossible.
Despite all of the choices that have opened up to women in the past few decades, there remains one sad reality: the biological clock waits for no one. Our opportunities are endless, but our egg supply and egg quality just simply are not. But as millions of women from the Sex in the City generation know all too well, plans change, relationships fail, and often finding Mr. Right or climbing to the top of the corporate ladder takes much longer than anticipated. The bottom line is women are facing a real challenge having successful pregnancies later in life.
But There is Hope
Until recently, egg freezing has been offered to women of reproductive age for medical reasons such as a diagnosis of cancer requiring chemotherapy or radiation that would render them infertile. However the chance of a successful pregnancy has been patchy given that eggs, on their own, are often too fragile to survive the freeze/thaw process. Unlike egg freezing, embryo freezing has been successfully performed since the early 1980′s with many clinics reporting successful pregnancies from frozen embryos comparable to that from a fresh IVF cycle. It has been difficult to freeze eggs as they are made up of a single cell, containing a large amount of water, creating ice crystals in the eggs at the time of freezing and ultimately damaging them during the freeze / thaw process. However, in the past 5-6 years advances in egg freezing methods have significantly improved the success rates and have reached a point where it is a viable option to women to preserve their fertility, not just for medical reasons, but also for social reasons such as pursuing a career, or not having found Mr. Right.
Since 2006 embryologists started experimenting with different freezing processes such as vitrification ( rapid freezing ) and slow cooling. This reduced the ice crystal formation in the eggs at the time of freezing which lead to higher survival rates at the time of thawing. Prior to 2007 only a few births were reported from frozen eggs, however since then approximately 1500 babies have been born world wide.
According to some studies in women less than 36 years of age the chance of a successful pregnancy from frozen eggs is close to 50%, which is actually comparable to the success rate using fresh eggs from women that age. The number of eggs needed to be frozen from women even in their mid thirties to achieve this chance of success is approximately 10-20 eggs depending on the medical practice guidelines. This would mean that a woman would often have to undergo more than 2 cycles of hormone injections to stimulate the ovaries to produce eggs. A greater number of eggs are required as many eggs are not genetically normal especially as age increases, Studies are being done to identify the genetically normal eggs, which are more likely to create a normal embryo, and hence freezing only those eggs, and thus improving the overall birth rates.
Peak reproductive potential is between 15-28 years of age when the egg quality is the best. Between 29-38 years of age many eggs are still of a good quality and in the later reproductive years 39-44 years, there is a marked decline in the quality of the eggs resulting in lower chances of pregnancy. Eggs frozen at age 35 have a better chance of producing a pregnancy than eggs frozen at age 44. Ideally, if women are freezing eggs for future reproduction, it should be done in the peak reproductive years to have the best shot at getting pregnant.
To date there does not appear to be a higher risk of birth defects in the children born from egg freezing. However the ASRM has labeled the procedure as experimental because the number of births is still too small to say if it is completely safe, as we do not know the long term repercussions. There are also some unanswered questions as to how long the eggs can be safely frozen, as many women will use their eggs 5-10 years after they have been frozen. Preliminary data suggests that frozen eggs may last for at least 10 years.
In contrast, embryo freezing is a well established form of assisted reproduction, with the first frozen baby born in 1984. It allows multiple embryo transfers from a single egg collection, increasing the chance of a live birth. Many clinics have pregnancy rates with frozen thawed embryos comparable to those achieved with a fresh embryo transfer. Women who wish to freeze their eggs, should strongly consider freezing embryos if that is an option for them. Embryo freezing has a long track record of producing successful pregnancies and is not an experimental procedure. Of course creating embryos would mean finding Mr. Right, or using donor sperm.
The point is, don’t underestimate the importance of your age when considering your fertility options.
Dr. Lalwani may be contacted 36