The new techniques for PGD have provided a mechanism for studying the genetics of the early human embryo. In addition, implantation failure, which increases with age, has been shown to be reflected in higher rates of aneuploidy in embryos from older women.  
 
The use of FISH for diagnosis in couples who are translocation carriers is also a possibility, such couples carry an increased risk for miscarriage and chromosomally abnormal fetuses. Polar body and blastomere biopsies can detect the fate of a maternally derived chromosomal translocation.  
 
Finally, PGD assessment of aneuploidy in chromosomes X, Y, 21, 18, 16 and 13 may be used to screen embryos from patients over 35 years of age. Presumably, this would allow discrimination of embryos that have a lower chance for implantation or a greater risk for miscarriage.