A woman’s fertility begins to decline in her thirties, so that by her forties, there’s a one-in-six chance that she’ll conceive. Given that more and more women are waiting to start families until later in life, many have hoped for a procedure that would allow them to push the pause button on the march of time. Enter ova storage, also called the freezing of eggs or, in medical terms, oocyte cryopreservation. In this procedure, a woman’s egg is removed from her body and frozen until a later point, when it is thawed. After undergoing in vitro fertilization, the new embryo can be implanted in the woman’s uterus to make her pregnant.

This technology was first applied in the mid-1990s for young women with cancer who had to undergo chemotherapy or radiation that destroyed their egg supplies. Before the cancer treatment, fertility treatments are needed to stimulate egg production. Then a needle is inserted through the vagina to retrieve the eggs. They are placed in thin tubes, which are then placed in a machine that freezes them. After freezing, the eggs are transferred to a storage bank cooled with liquid nitrogen to a temperature of –321°F.

The trouble with ova storage is that eggs are more fragile than sperm: Water in the cell can turn into ice, putting pressure on the cell and damaging or even rupturing it. One study found a pregnancy rate of about 17 percent with the use of frozen ova.

ADDITIONAL FACTS

  1. It costs about $10,000 to $15,000 to harvest and freeze a batch of eggs.
  2. Storage costs about $500 a year.
  3. There are two methods of freezing the egg: dropping the temperature rapidly or slowly lowering the temperature while protecting the egg with solutions called cryoprotectants, a process called vitrification.