Oocyte Cryopreservation directly translates as ‘Egg Freezing’ in common man’s language. Human Oocyte cryopreservation is a process in which a woman’s eggs (oocytes) are extracted, frozen and stored, as a method to preserve reproductive potential in women of reproductive age.
An oocyte is an immature egg cell which eventually matures to become an ovum or egg. This egg is then released during ovulation, a process which occurs once, mid-way through a female’s monthly cycle. If a sperm meets and fertilizes the egg, an embryo is formed else the egg is discarded resulting in menstruation.
A woman is born with all the oocytes (eggs) that she will ever have – approximately 2 million or less. At puberty, when she develops the hormonal capacity to take the eggs to complete maturity, the number of eggs remaining is already down to 300,000. Though she will only need 300 to 400 eggs in her lifetime, but by her mid-30s, the eggs that remain are of lower quality, as the best and most responsive eggs have already matured and died in the absence of fertilisation. Thus a woman’s increasing age effects a decline both in the probability and quality of her fertility.
Human Oocyte Cryopreservation or Egg freezing helps a woman preserve quality eggs which mature in her 20’s, and use them in the future to have biological children when is ready for them. This helps her take control of her life and not rush to start a family because the biological clock is ticking away.
The Oocyte Cryopreservation technique involves four key steps:
- The woman has to undergo one to several weeks of hormone injections that stimulate her ovaries to ripen multiple eggs;
- The eggs are subsequently removed from the body;
- The eggs are frozen using a flash-freezing process known as vitrification;
- The frozen eggs are transferred to a liquid nitrogen storage chamber for storage.
Statistics, though limited, suggest that the eggs have the same chance of becoming a baby when frozen and used later, as they would if freshly fertilized and used in an IVF cycle. However, that chance is determined by the woman’s age at the time of freezing the eggs. The highest live birth rates from previously frozen eggs are shown to have come from women who froze their eggs in their early 20’s or before they turned 30. Hence, to achieve a high probability of success at a live birth in the future, it is advised that women wanting to freeze eggs do so in their 20’s or best before the age of 36.
Oocyte Cryopreservation is advisable for:
- Women diagnosed with cancer:
- In case of women suffering with cancers of the reproductive system, the treatment might involve surgery to remove a crucial part of the reproductive system thereby making it impossible for the woman to conceive on her own.
- In other cases of cancer, surgeries, chemotherapy and radiation treatments can cause toxic damage to the oocytes hampering the woman’s fertility.
- Women undergoing treatment with assisted reproductive technologies like IVF, and object to embryo freezing for ethical or religious reasons;
- Women with medical reasons like a family history of early menopause, endometriosis, PCOS etc.;
- Women who have not yet found their ideal life partner with whom they would like to start a family.
However, Oocyte Cryopreservation is becoming increasingly popular with progressive urban women who want to consider marriage and pregnancy at a later stage in life due to education or career priorities, or becoming financially sound, or just any personal reason. ‘Social egg freezing’ is a term coined to describe this practice of freezing a woman’s eggs for non-medical reasons. This is also referred to as ‘Elective Oocyte Preservation’.