Fertility Preservation for Women
What is fertility preservation?
A woman is born with 1 to 2 million eggs (oocytes) in her ovaries. This supply comprises all the eggs she will have during her lifetime. These eggs mature and are shed in a normal process similar to the daily loss of skin or hair cells. Unlike these cells, oocytes do not regenerate. The normal oocyte loss rate increases as women enter their mid-30s (approximately 15 years before menopause). The decline in the number of eggs, as well as their quality, is one reason why women in their 30s and 40s often experience difficulty conceiving a pregnancy. Some women lose fertility earlier than normal due to a chronic or unexpected illness, or accident. These are just a few of the many reasons why women may wish to preserve their fertility by freezing eggs or embryos.
In some cases, patients with a chronic illness, such as cancer or lupus, need to take drugs which may accelerate ovarian aging and hasten the onset of menopause. Increasingly women are interested in preserving their eggs because they are busy achieving educational or vocational goals during the years that their fertility potential is highest, or they are not in stable a social situation conducive to pregnancy. This includes single women who may be without male partners and wish to preserve fertility by freezing eggs for a later date.
What can I expect from the procedure?
Freezing eggs or embryos generally follows this process:
- A woman consults a reproductive endocrinologist (fertility specialist). During the initial visit, the specialist will review her health history and discuss the pros and cons and realistic expectations for freezing eggs or embryos. Because normal aging can compromise egg quality, cryopreservation will be more successful for a woman in her 20s or early 30s, than for an older woman nearing age 40.
- The treatment involves daily injections of hormones (gonadotropins), for 10 to 12 days. The patient self-administers these injections. The medication will stimulate multiple eggs to mature at the same time. Egg maturation is closely monitored through frequent morning office visits, where blood tests and pelvic ultrasounds are performed to assess the ovaries’ response to the medications.
- Once the eggs are mature, the woman undergoes a minor outpatient surgical procedure to aspirate the eggs from her ovaries.
- After the woman receives a local anesthetic, a specialist performs the 10-minute procedure by placing a needle into the ovary under ultrasound guidance to locate and remove the mature eggs. The eggs are then frozen and stored in the laboratory.
Because pregnancy rates from frozen and thawed oocytes are still much lower than from frozen embryos, some women opt to use sperm to create embryos, which are frozen for future use. Even for younger women (under age 35), predicted pregnancy rates are between 2 to 6% per cryopreserved oocyte, versus 30 to 50% per cryopreserved embryo. These rates will be lower for older women (over 35).
Cryopreserving either part of or an entire ovary for future use is another method of fertility preservation currently under investigation. While there have been isolated reports of female cancer survivors successfully conceiving after having ovarian tissue removed, then re-implanted, this method is still considered highly experimental.
Currently, embryo or oocytes cryopreservation appears to be the most reasonable way for women of childbearing age to preserve their fertility. However, the clinical benefits of these procedures have not been well studied, particularly in healthy women who choose this method to preserve fertility. It is not clear how to identify those patients who might conceive naturally and easily at a later age, and who might not need to undergo treatment and subsequent cryopreservation. Other patients might discover that their carefully cryopreserved oocytes or embryos will not produce a future pregnancy.
Because outcomes are uncertain, and many factors affect the treatment process, the first step for a patient looking into fertility preservation should be to consult with a reproductive endocrinologist to begin an open discussion about the potential benefits and pitfalls of fertility preservation treatments.