By Chioma Umeha
Women today are choosing to have children later in life than ever before. Egg freezing, technically known as oocyte cryopreservation, can enable a woman to delay pregnancy until a later stage.
In 1980, the average American woman had her first baby at the age of 22. By 2000, that age had risen to almost 25, and in 2014, the average woman waited until the age of 26 to have her first child.
In the United Kingdom, the number of women having children over the age of 40 years has tripled since 1980. In 2016, more British women over 40 years old gave birth than those younger than 20 years old. In the United States, 2.3 per cent of all births are to women aged 40 to 44 years.
Society may be changing, but the biological realities of fertility remain the same. Most women enter menopause in their late 40s or early 50s. In the years before menopause, a woman’s fertility declines. Although the life experience of an older woman may mean she is well equipped to be a mother, conceiving is not as easy as it is for a younger woman.
Women who are considering freezing their eggs should be aware that successful pregnancies are less common with frozen eggs than with fresh eggs. However, the use of frozen eggs can offer a hope of conceiving in the future, when previously it was impossible.
What is egg freezing?
As a woman ages, the quality of her eggs tends to decline; the eggs may contain more chromosomal abnormalities, and after menopause, women will no longer ovulate.
If a woman wants a child but is not able or ready now, she can have her eggs frozen for use at a later date.
Before the egg-freezing process begins, a doctor will take a comprehensive fertility history, assess a woman’s menstrual cycle, and do blood work to assess hormone levels.
A woman’s ovaries usually release just one egg per month. The fewer eggs there are available to freeze, the fewer chances there are of successful pregnancy.
In order to maximize the number of available eggs, a woman will undergo hormone treatment to stimulate her ovaries to produce more eggs. This treatment normally requires a woman to inject herself with hormones at home, from one to three times a day.
The number and type of hormones given varies from woman to woman.
Treatment will normally include:
• Around two weeks of injections with follicle-stimulating hormone (FSH) and luteinizing hormone, which encourages the ovaries to produce more eggs
• An injection of gonadotropin-releasing hormone (GnRH) about halfway through the cycle, which prevents ovulation from happening too early in the cycle
• An injection of human chorionic gonadotropin (hCG) to trigger ovulation
A doctor will perform regular blood work to assess the effects of hormone treatments. The woman will also have at least one ultrasound to detect ovulation and to assess egg development.
When the eggs ripen, the doctor will insert a needle into the woman’s ovarian follicles to retrieve the eggs. The doctor will normally use ultrasound to guide the procedure, but if the eggs are not visible through ultrasound, the doctor may perform abdominal surgery to remove them.
With this more invasive approach, the doctor will make a small incision in the woman’s abdomen to insert a needle and extract the eggs. The woman will have been sedated and received pain medication.
Once the eggs have been retrieved, they will need to be frozen as soon as possible. The eggs are full of water, which can turn into damaging ice crystals if the eggs are frozen immediately. To prevent this, the doctor injects a special solution into the eggs before freezing them.
When the woman is ready to use her eggs, she will undergo in vitro fertilization (IVF).
With IVF, the egg is fertilized in a lab, using sperm either from the woman’s partner or from a donor. If the procedure works, the egg and sperm develop into an embryo that is implanted into the woman’s uterus a few days later. Most fertility clinics try to grow several embryos at once to increase the chances of a successful pregnancy.