Should mosaic embryos be transferred?

The honest answer is that nobody knows for certain, and you should be wary of anyone who tells you otherwise. ESHRE's position is direct: the clinical significance of transferring mosaic embryos is currently unknown. That is the current state of knowledge, not a gap waiting to be filled next year. What is known is that transfer could potentially carry a risk of first-trimester miscarriage, or of a baby with an unbalanced chromosome result. How large those risks are is not established. What ESHRE requires of your clinic: It should have a documented policy on identifying and transferring mosaic embryos, and share that policy with you during genetic counselling. If a mosaic embryo is transferred and pregnancy results, appropriate follow-up should be arranged. Where this usually arises is when mosaic embryos are the only ones available. That is a genuinely difficult decision, and the considerations include your age, whether further retrieval cycles are realistic, what the specific chromosome finding is, and your own view on the uncertainty involved. Questions worth asking: What exactly was found, and which chromosomes? What is this clinic's policy, and why? If I transfer, what follow-up would you arrange in pregnancy? What are my realistic alternatives? Genetic counselling before deciding is strongly worthwhile. This is not a decision to make in a phone call about your results.