The more eggs frozen, the better your chances of pregnancy
A recent study by Dr. Cobo from Valencia, Spain, looked at 3,467 warming cycles of eggs after elective egg freezing in patients less than 35 years old for donation to another individual. (This included data on 378,087 eggs!!) Each recipient got approximately 8-10 eggs to thaw per cycle.
Survival rate was 90 percent, similar to prior studies, but only a result seen in clinics that are highly specialized to do egg freezing (such as RSCBA). Implantation rates per embryo were 39 percent, as were ongoing pregnancy rates. Seventy percent of cycles had extra embryos to freeze, as approximately two embryos were transferred from the original 8-10 eggs.
The oocyte (egg) to baby rate was 6.5 percent. The live birth rate increased progressively as the total number of eggs frozen increased.
Because of the large number of eggs that were included in this study, we now have more data about how many eggs to thaw and what the expected pregnancy rates are to help counsel patients. For patients who are under 35 and desire to freeze their own eggs for the future, this is a helpful study to show that the more eggs in storage the better.
Unfortunately, it was not possible to estimate the success of thawing based upon baseline characteristics, stimulation parameters or length of cryostorage. Therefore, we are still left with trying to freeze more than a woman might need to play it safe.
Should you consider egg freezing?
More and more women are turning to egg freezing to increase their options for motherhood. I generally see three types of people who can benefit from egg cryopreservation.
Women who will soon undergo fertility-damaging medical treatment, such as cancer treatments involving radiation and chemotherapy, may want to consider egg freezing. These cancer treatments often harm healthy cells, including a woman’s eggs. Often times this decision needs to be made quickly, because during the time between diagnosis and treatment we must arrange for egg retrieval. Other medical conditions that can disrupt fertility can make egg freezing a viable option.
Women who are undergoing in vitro fertilization (IVF) or other assisted reproductive technologies, but who don’t want to freeze embryos, generally for moral or religious reasons, may opt to freeze eggs. The unfertilized egg can be thawed in the future and create an embryo through IVF used to achieve pregnancy.
Women may wish to freeze their eggs for “social” reasons. These are non-medical reasons, such as not wanting to take time off from a career to be a mother or not having found the right partner yet. For these social reasons, women choose to freeze their eggs at a younger age when the eggs are more plentiful and viable.