Prenatal diagnosis of chromosomal disorders is generally offered to women w
ho will be 35 years or older at the rime of delivery or who have been deter
mined via serum screening to be at risk similar to that of a woman older th
an 35 years. This age threshold was based on 4 major rationales that reflec
t considerations of resources and effectiveness. In this paper, we explore
the current screening recommendations and consider new information that cal
ls the 35-years threshold into question. We conclude that guidelines regard
ing use of prenatal diagnosis account for the preferences of the individual
patient as well as for individual risk.