In Utero: Gene Transfer Nirvana?

The February 2008 issue of Molecular Therapy has an editorial by Charles Coutelle defending in utero gene transfer (that is, the application of gene transfer to fetuses).  Coutelle makes several attractive arguments in its favor.  Among them: that many parents opt against abortion after receiving  a prenatal diagnosis, and that in utero gene transfer would provide these parents with a therapeutic option.

What troubles me about this position is this:  1- what makes in utero gene transfer attractive–favorable "vector-to-cell" ratio, and the "presence of expanding and developing stem cell populations," is precisely what makes this procedure risky as well; 2- how often do parents opt against pre-implantation diagnosis, but then go on to seek prenatal pregnancy screening?  Specifically, does the frequency of the latter justify the risks of the former?