QUESTION: My partner and I are deciding on how many eggs to fertilize with our sperm. What are the odds that two eggs will result in one fetus? If we’re sure we only want one child, how many embryos do you suggest?
Dr. Doyle: Usually if the egg is mature and the sperm is reasonably normal, the chance of fertilization is approximately 80-90%. Then about half of those eggs that fertilize develop into strong viable embryos are suitable for transfer, and only about half of those implant, usually because many of the others have chromosomal imperfections. This is why starting with more eggs (ideally at least ten) may be necessary to ensure that you get even one baby. If you put in two of your highest quality embryos, the chances of twins is usually around 40% so parents like you who definitely only want one baby should only transfer ONE embryo at a time.
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