There’s no doubt about the marvel of in vitro fertilisation, or the brilliance of the scientists who pioneered it. But there’s an element of the technique which is causing a little-known and serious ethical dilemma. What do couples do when they complete IVF treatment without using all their embryos? Destroy the leftover ones? Or donate them to other want-to-be parents? Allison Langdon reports that while embryo donation can be the most generous gift of all, it also comes with risks, and one very tough question: just what are the implications of giving your unborn child to a complete stranger?