Egg freezing allows individuals to preserve their fertility by collecting and storing eggs at a younger age when they are typically of higher quality. This process extends their reproductive timeline, offering flexibility for future family planning.
Key Considerations for Egg Quantity
Determining the appropriate number of eggs to freeze involves several factors, primarily age. As individuals age, both egg quantity and quality naturally decline. Younger individuals generally have eggs with a higher likelihood of resulting in a live birth, meaning fewer eggs may be needed for success.
For example, women under 35 might consider freezing 15 to 20 mature eggs for a strong chance of at least one live birth. Those aged 35 to 37 may aim for 20 to 25 eggs, while individuals 38 and older often target 25 to 30 eggs or more, as success rates decrease with advancing age.
The number of children an individual hopes to have also influences the target egg count. For one child, a lower number might suffice, especially if frozen at a younger age. For multiple children, aiming for a higher number, potentially 20 to 30, can increase the chances of viable embryos.
Ovarian reserve, reflecting the number of eggs remaining, also plays a role in retrieval yield. This reserve is assessed through tests like Anti-Müllerian Hormone (AMH) levels and Antral Follicle Count (AFC). Higher AMH and AFC generally indicate a greater egg supply and potentially higher yield per cycle. Individuals with lower ovarian reserve might require multiple retrieval cycles to accumulate the desired number of eggs.
Understanding Live Birth Success Rates
The ultimate measure of success in egg freezing is the live birth rate, which depends significantly on the age at which eggs were frozen and the number of viable eggs stored. For instance, freezing 15 mature eggs for women under 35 offers an estimated 80% chance of at least one live birth. This probability decreases with age: for women aged 38 to 40, 30 eggs may yield a 75% chance, while for those 40 to 42, 30 eggs might offer a 50% chance.
Not every frozen egg will result in a live birth due to attrition. After thawing, approximately 90% of eggs typically survive. Of those, about 70% may successfully fertilize. Around 40% of fertilized eggs are expected to develop into good-quality embryos.
Further attrition occurs during embryo transfer and pregnancy. A single embryo may have about a 45% chance of developing into a clinical pregnancy for women under 35. This multi-step process means a higher number of eggs must be frozen initially to account for potential losses and maximize success.
The Egg Retrieval Process
The egg retrieval process begins with ovarian stimulation, where individuals receive hormone injections to encourage multiple follicles in the ovaries to mature. This controlled stimulation aims to produce more eggs than would naturally mature in a typical menstrual cycle. Throughout this phase, medical professionals closely monitor the development of the follicles using ultrasounds and blood tests to track hormone levels.
Once the follicles reach an optimal size, typically after 8 to 14 days of stimulation, a final injection is administered to trigger the eggs’ full maturation. The egg retrieval procedure is then scheduled about 36 hours later.
This is a minor surgical procedure performed under light sedation, usually in an outpatient setting. During the procedure, a thin needle guided by ultrasound is used to gently collect the mature eggs from the ovaries.
What Happens Next
When an individual decides to use their frozen eggs, they are carefully thawed in a laboratory setting. While modern vitrification techniques boast high survival rates, not all thawed eggs will survive. Surviving eggs are then fertilized with sperm, typically using intracytoplasmic sperm injection (ICSI), where a single sperm is injected directly into each egg.
Following fertilization, resulting embryos are cultured in the lab for several days. Not all fertilized eggs will develop into viable embryos suitable for transfer. The most promising embryo or embryos are then selected and transferred into the uterus, aiming for implantation and a successful pregnancy. This sequence completes the journey of the frozen eggs.