Late last year, Jack and Lisa Nash, a Colorado couple, opted for the high-tech approach to avoid their new baby suffering from Fanconi anaemia, a rare inherited bone-marrow disease, which plagues their daughter.
It is a particular gamble if the child is conceived partly to provide a bone marrow graft for a brother or sister with a nasty genetic disease: not only might the new baby turn out be a poor match for transplantation, but might also have inherited the same disorder as his or her sibling.