Unlike men who make sperm throughout life, women are born with all of their eggs. In fact it is estimated that at birth a woman will have 2 million eggs. This number reduces throughout life and by puberty this number has fallen to approximately 300,000! Consequently your chance of being able to become pregnant decreases as your age increases, especially after the age of 35. Recent scientific advances now allow a woman the option of freezing and preserving eggs if you are not ready for pregnancy now but want the best chance in the future.
Women chose to freeze eggs for a number of reasons, both medical and non-medical. Medically, for example, if a woman is diagnosed with cancer, she is likely to require chemotherapy or radiation. These treatments will often result in infertility due to damage to her eggs. If she has frozen her eggs prior to her treatment she has a chance to use these in the future, allowing her to have a baby when she would possibly not have the chance without having been able to store eggs prior to her cancer treatment.
Other women may still be waiting to meet the right partner to have children with, or wish to concentrate on their careers, and see egg freezing as a way of preserving their fertility. The number and quality of eggs a women has begins to decline dramatic after the age of 32. Sadly this means that even with techniques as advanced as IVF, having a baby becomes much more difficult in the late 30’s or early 40’s for some women. The development of egg freezing technology offers tremendous hope and now presents the option for women to have eggs stored at a younger age, thereby preserving their fertility options. When these women decide they are ready to try for a baby, they have the ‘younger’ eggs stored as a back-up in case they have problems becoming pregnant on their own.
The egg freezing technique involves collecting eggs from you in the same way as if you were undergoing a cycle of IVF. The mature eggs are then frozen the same day. When you are ready to be pregnant, your eggs are thawed and fertilised via IntraCytoplasmic Sperm Injection (ICSI). Resulting embryos are then transferred to your uterus.
Egg freezing has been more of a challenge scientifically than the freezing of embryos because the egg is the largest cell in the human body and contains a lot of water. During the freezing process, this water may turn to ice crystals, which could destroy the egg. Until vitrification (a rapid freeze technique) was developed, previous attempts at egg freezing were not very successful. However, published data show that 99% of eggs preserved by vitrification survive and 92% fertilise successfully when warmed. Implantation rates and pregnancy rates are in keeping with women having IVF treatments at the age at which the eggs were frozen. This is an important consideration when you decide to freeze your eggs at an older age. The rate of chromosomal and birth defects of these babies has been no higher than in babies born from ICSI with fresh eggs from women at the same age.