Can mosaic embryos become healthy babies?

Some have. That is the honest answer, and the equally honest follow-up is that the clinical significance of transferring mosaic embryos is currently unknown — that is ESHRE's own wording. Healthy babies have been born following transfer of embryos reported as mosaic. That is well documented. What is not established is how often, for which findings, or how to predict which mosaic embryos will do well. Why it is possible at all: the biopsy takes a few cells from the outer layer that becomes the placenta. A mosaic result tells you those cells were mixed. The cells that become the baby may be entirely normal. What ESHRE says should happen: Your clinic should have a documented policy on identifying and transferring mosaic embryos, shared with you during genetic counselling. If a mosaic embryo is transferred and pregnancy results, appropriate follow-up should be arranged. Transfer could potentially carry a risk of first-trimester miscarriage or of a baby with an unbalanced result. Be cautious of confident percentage-based rankings of mosaic embryos. Detecting changes present in less than roughly 20 to 30% of a small sample is very difficult, and detection is specific to each laboratory's platform — so a threshold validated at one laboratory does not transfer to another. If mosaic embryos are all you have, this becomes a real decision. Ask for genetic counselling, ask what exactly was found, and ask what follow-up would be arranged in pregnancy.