It sounds like an Aldous Huxley novel.
A couple conceives one child through IVF, saves an extra embryo for future use, but then an accident happens in the lab. The couple's last embryo is mistakenly implanted in a woman...who then aborts it, upon finding it is not her own child. Perhaps this is why human beings should leave the life-and-death decisions to God.
Read the full story here: http://www.lifesitenews.com/ldn/2009/jun/09061509.html