I have NFI who these people are either, but a G search eventually lead to a wikipedia page about selective reduction (which J&K declined to go ahead with). What a horrible thing, WTF are doctors going to think of next?
Selective reduction (or fetal reduction) is the practice of reducing the number of fetuses in a multifetal pregnancy (those involving more than one fetus). With selective reduction, one or more fetuses are "selected" for termination.
http://en.wikipedia.org/wiki/Selective_reduction