Last year, Kourtney Kardashian made headlines when she decided to freeze her own eggs. The process, called oocyte cryopreservation, is a fertility procedure available to women of childbearing age. Nowadays, more and more women are choosing to first prioritize their education and careers before pursuing motherhood. The science behind freezing your eggs means the initial harvest only requires a few weeks of fertility drug protocol. Since egg quality and quantity both decline as women age, egg-freezing solves the problem of the infamous ticking biological clock.
Preparing For Egg Retrieval
Fertility doctors, called reproductive endocrinologists, are able to use special drugs that help a patient produce extra eggs during their typical menstrual cycle. These drugs aren’t available at the average pharmacy and can cost several thousands of dollars. Unfortunately, most of the prescriptions have to be injected. This can often be the most uncomfortable part of the egg maturation process. Other common side effects include mood swings, headaches, insomnia, breast tenderness, and bloating.
Over the course of these egg-producing prescriptions, the patient will receive several transvaginal ultrasounds to monitor egg maturity and quantity. To prevent complications, nurses will draw blood every few days. These blood draws will show hormone levels and allow doctors to adjust dosages if needed. After about two weeks of egg-producing drugs, the mature eggs are ready to be retrieved.
How Eggs Are Retrieved & Frozen
When transvaginal ultrasound reveals the eggs are mature, the reproductive endocrinologist retrieves them through a simple outpatient procedure. Patients go under anesthesia for the ten- to fifteen-minute process. Using a needle, the doctor reaches the ovaries through the vaginal wall. Eggs are then drawn into the needle, which is attached to a catheter. The catheter leads to a tube, which an embryologist will then freeze using cryogenic techniques.
Mature eggs are frozen almost immediately through a process called vitrification. This fast-freeze reduces the chance for ice crystals to form and damage the eggs. Frozen eggs are then transferred to “cryo-tanks”, which are then transported to long-term storage facilities. The best storage facilities include several layers of security and viability. To cope with a potential loss of power, most cryogenic facilities have multiple generators and even liquid nitrogen stores on-site.
Pregnancy Success Rates With Frozen Eggs
According to the Extend Fertility clinic, live birth rates appear nearly identical between frozen eggs and fresh eggs. In one of the largest studies, 600 couples were randomly assigned the use of frozen eggs or fresh eggs to use during typical in-vitro fertilization (IVF) cycle. Both frozen and fresh eggs showed similar rates of success in both attaining pregnancies and in achieving a live birth.
Maternal Age Matters
The most significant factor in freezing eggs (and their eventual thawing and fertilization) is the maternal age at the time of retrieval. People with uteruses and ovaries are born with all the eggs they will ever have - they don’t produce eggs during their lifetime. This number of eggs is called the “ovarian reserve”, and the average person has about one million eggs at birth. Once the patient enters puberty, they begin to lose about 1,000 eggs per month.
Advancing maternal age also negatively impacts the quality of eggs. As patients age, their remaining eggs have a higher likelihood of harboring a significant genetic abnormality. The decline in egg vitality tanks as women approach their fortieth birthday. Women aged 25 to 30 have the healthiest eggs: about 75% of their eggs are chromosomally normal. Between 31 and 35, that number drops to 65%. Ten years later, only 20% of eggs show a normal chromosomal make-up.
This factor of maternal age is exactly why more and more women, like Kourtney Kardashian, are choosing to freeze their eggs during their twenties and thirties. Women might not be ready to take that step into motherhood in their early years - but they’d like to keep the option for carrying their own biological children open. Egg freezing is just one way to delay - but not rule out - the option to have children later in life.