Embryo banking, or embryo freezing, is the most established method of fertility preservation, with decades of success and extensive published outcome data. This method has resulted in the births of hundreds of thousands of babies worldwide. It involves freezing embryos created from a woman’s eggs and a partner’s (or donor’s) sperm for future use, making it a reliable option for those looking to preserve fertility.
To begin the process, a woman undergoes ovarian stimulation, where daily hormonal injections encourage the ovaries to develop multiple mature eggs. Once the eggs are ready, they are retrieved through a minor procedure using a thin needle, guided by ultrasound, which is performed under sedation. After retrieval, the eggs are fertilized with sperm, and the resulting embryos are cultured for a few days before being frozen for future use.
Embryo freezing is a standard procedure for both medical and social fertility preservation, unlike egg freezing, which is still considered experimental when done for social reasons. Since embryo freezing requires sperm, it may not be the best option for women who do not have a committed partner. As a result, many single women opt for egg freezing instead. However, for couples in stable relationships, embryo freezing remains the most established and reliable method of social fertility preservation.
The process of embryo freezing takes a few weeks, which may not be feasible for newly diagnosed cancer patients who are scheduled to start chemotherapy or radiation soon. Even when time allows for a freezing cycle, one cycle may not produce enough embryos to ensure a high probability of future pregnancy. Studies suggest that cancer patients typically generate around eight embryos per cycle, which might not be sufficient. In such cases, other fertility preservation options, like ovarian tissue cryopreservation, could be a more suitable choice, depending on the treatment timeline.
Embryo freezing has considerable outcome data to determine how many embryos should be frozen in order to have a reasonable chance of future pregnancy. How many embryos a patient should freeze will depend on her age and ovarian reserve status. For younger women with normal ovarian reserve, CHR typically recommends freezing of at least 20 embryos. As embryos frozen later in life have a lower potential of leading to a pregnancy, women in their 30s and 40s should consider freezing significantly more. CHR physicians will counsel patients based on their individual circumstances.
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