By COREY BURKE
Women are increasingly waiting later in life to have children and start a family. While delaying having children is potentially helpful in building a career, it is often detrimental to reproduction. As the biological clock keeps ticking, many professional women are turning to assisted reproductive technologies (ART) to help them build a family. While ART can overcome many aspects of infertility, there are limitations; primarily a woman's oocytes. As women age the number of oocytes remaining in the ovaries not only decreases, but the number of aneuploid (chromosomally abnormal) oocytes increases. This one-two punch is significant and evident in the live birth rate for women having IVF over the age of 40. The live birth rate for women using their own eggs decreases almost 50% per cycle for women who are over 40, and by age 45 the live birth rate is nearly 0.
Until recently the only options available to women of advanced reproductive age was to use donated eggs or to adopt. While these remain the frequently used options, there is still a lack of a genetic connection between parent and child, which is of great importance to many. Technological advances now allow us to cryopreserve oocytes effectively and efficiently. Elective (social) egg freezing gives women the opportunity to preserve their fertility and have genetically linked babies when they are academically, professionally, and financially ready.
Why has this option taken so long to become widely available? Well, because prior to 2005, eggs could only be frozen using what embryologists call the slow freezing method. This method involves loading the cells with cryoprotectants and then slowly lowering the temperature to - 197 C. The problem with this method for freezing eggs is contained in the very name of the process, slow FREEZING. During freezing, liquids crystalize and in the transition phase, liquids and solids coexist. This process allows ice crystals to form and damage the tissue being frozen. In the case of embryos, some damage from ice crystals is ok because an embryo is multicellular and can survive some cell loss. Sperm, similarly, can withstand some damage from ice crystals because most samples contain many millions of cells and killing a few million has little overall effect on a sample. Eggs, however, are single cells and consist of mostly cytoplasm; any damage from ice crystals almost always results in cell death - making the process incredibly inefficient.
Now we have the process of vitrification! This is the transitioning of a liquid to an amorphous solid with no equilibrium between crystalline and liquid state, thus preventing the formation of ice crystals. Since there is no equilibrium state, vitrification is not actually freezing in the sense we commonly think of. In this process, eggs or embryos are loaded with cryoprotectant, like the slow freeze method, and then plunged into liquid nitrogen. This rapid cooling method turns the eggs and the liquid they are contained in to glass. Improvements over the past 10 years have led to an egg survival rate of close to 100% in well trained hands.
Pregnancy rates with vitrified eggs are similar to those of fresh eggs and provide an opportunity for women to "preserve" their fertility for medical reasons or to postpone starting a family. A woman who has her eggs vitrified in her twenties or early thirties will have an insurance policy of sorts if she finds she has fertility issues when she is ready to conceive. The vitrified eggs remain "frozen in time" at the age at which the woman was when the procedure was done. This is a huge advantage for women postponing childbirth when you consider that women under 35 undergoing IVF have a live birth rate of 54% and women aged 38-40 have a live birth rate of only 26%.
In 2012, the American Society of Reproductive Medicine (ASRM) removed the experimental label from oocyte vitrification, making it a routine clinical practice. This opened the door for fertility preservation for women. Prior to 2012 most egg vitrification was done for women with cancer or other disease states that impaired their fertility. In addition to the advantages already described, this has a social impact by leveling the reproductive playing field between men and women. Men have been able to freeze sperm since the 1950's and couples could freeze embryos, but you have to have sperm to make embryos. For the first time in history, women can cryopreserve their gametes for future use and control their own reproductive future.
The cost of fertility preservation ranges from $7000 - $15,000 per cycle. Depending on the age of the woman and her ovarian reserve, more than one cycle may be needed. The process takes approximately 2.5 weeks and involves several doctor appointments for ultrasounds and blood work to monitor the progression of the eggs' maturation. There are daily hormone injections that cause more eggs to mature than would in a natural cycle, allowing more eggs to be retrieved. The eggs are retrieved vaginally using an ultrasound guide and the procedure is completed in around 20 minutes. The egg retrieval is performed under IV sedation. After the procedure, some patients experience period-like symptoms, but most return to work the next day.
Oocyte vitrification has many advantages, and while called fertility preservation, it is not a guarantee of children in the future. There are many factors involved in achieving a pregnancy and eggs are just one. Simply having eggs in the freezer does not assure a good uterus, sperm, or endocrinological support. It should also be noted that having stored eggs does not necessarily mean the woman will ever need them. Many women have children into their forties with little problem. Fertility preservation should be looked at as an insurance policy that may never be needed.
For further details please call 407-203-1175
