Chuck Bednar for redOrbit.com – @BednarChuck
An increasing number of women are freezing their eggs because they’re not yet ready to have children and they want to keep the door open to start a family later in life. In fact, The Daily Mail recently reported that demand for the procedure in the UK has risen 400 percent.
While it can be difficult to choose the right time to become a mother, in the past, it has been equally challenging for a woman to decide what is the best time to have her eggs frozen. Now, however, Dr. Tolga B. Mesen, an obstetrician and gynecologist at the University of North Carolina, Chapel Hill’s Fertility Clinic, and her colleagues have calculated the ideal age.
As the authors wrote in the journal Fertility and Sterility, they set out to estimate “the optimal age to pursue elective oocyte cryopreservation.” They used a model “constructed to determine the success and cost-effectiveness of oocyte preservation versus no action when considered at ages 25–40 years, assuming an attempt at procreation 3, 5, or 7 years after initial decision.”
In other words, as Science explains, Dr. Mesen and her fellow researchers considered a variety of economic and biological factors to determine the ideal age for women to have their eggs frozen if they want to become pregnant and start a family as late in life as humanly possible.
Finding the “sweet spot” for freezing oocytes
There are two main factors to consider when determining when it is best to freeze a human egg, according to Science: the viability of those eggs once thawed, and how much it will cost to keep the oocytes preserved. The longer a woman waits to freeze her eggs, the less likely it is that they will result in a live birth – but in terms of dollars, older women benefit the most, since they often have fewer years of fertility left.
As part of their research, the UNC-led team collected data from national registries and surveys of pregnancies and fertility treatments, as well as ongoing studies on conception rates and medical records from fertility clinics all over the country. They then created their decision-tree models to calculate the probability of live birth when a woman either froze her eggs for a specific amount of time or opted to wait to try to get pregnant naturally or through IVF.
They found that egg freezing was most beneficial to women when the wait period was seven years, as it increased the chances of a live birth for women of all ages (though that increase was minimal for women 32 years of age of younger, according to Science). The largest improvements were observed when eggs were frozen at age 37, as the probability of a successful live birth at 44 years of age increased from 21.9 percent to 51.6 percent.
Furthermore, the study authors concluded that most women would have to freeze their eggs by the age of 34 in order to have at least a 70 percent chance of giving birth to a live child. Since the researchers also found that egg freezing provided the most improvement in live birth rates versus not freezing until after age 30, Dr. Mesen told Science that she and her colleagues believe the so-called “sweet spot” for freezing ages in between the ages of 31 and 33.
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