From the Research
From 7 eggs retrieved, you can typically expect 2-4 embryos to reach the blastocyst stage by day 5, considering the most recent and highest quality studies available. This number varies based on several factors including egg quality, sperm quality, maternal age, and overall fertility health. The progression typically follows a pattern where about 70-80% of mature eggs will fertilize, then about 50-60% of those fertilized eggs will develop to day 3, and finally about 30-50% of those will reach the blastocyst stage by day 5 1.
Some key factors influencing the outcome include:
- Egg quality: The quality of the eggs retrieved plays a significant role in determining the number of embryos that will reach the blastocyst stage.
- Sperm quality: Similarly, the quality of the sperm used for fertilization can impact the success rate of embryo development.
- Maternal age: Women under 35 tend to have higher rates of blastocyst formation compared to those over 38 2.
- Fertility conditions and laboratory protocols: Underlying fertility conditions, laboratory protocols, and individual biological variations can also influence the outcomes.
It's essential to note that the relationship between the number of oocytes retrieved and pregnancy is nearly a reflection of the pattern of the relationship between the number of oocytes retrieved and the probability of having two good-quality embryos transferred 1. Therefore, selecting the desired number of good-quality embryos for transfer is the key to IVF success.
Understanding these expected numbers can help manage expectations during the IVF process, though your reproductive endocrinologist can provide more personalized estimates based on your specific situation. The most recent studies suggest that ICSI does not bypass the age-related decrease in oocyte quality in patients using donor sperm for IVF, and the use of ICSI was associated with lower rates of high-quality embryos 2. However, the choice between IVF and ICSI should be based on sperm characteristics rather than using ICSI for all cases 3.