While the success with IVF literally only requires one normal embryo, patient outcomes improve with a reasonable number of eggs retrieved, typically 10-15 mature eggs. Actually, studies have shown that egg quality may be reduced if retrieval results in an excessively high number of eggs. Of the eggs retrieved, approximately 60-80% are mature and of these, about 70-80% will fertilize. Once an embryo divides, it has a 50-60% chance of developing into a day 5 blastocyst which is most optimal for implantation or freezing.
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