Preimplantation genetic diagnosis and human implantation--a review.

By selecting chromosomally normal embryos for replacement, PGD for aneuploidy can (i) increase implantation rates, (ii) reduce spontaneous abortion rates, and (iii) avoid aneuploid conceptions. When eight chromosomes are analysed, a significant increase in implantation is achieved. PGD is also found to significantly reduce the incidence of spontaneous abortion and chromosomally abnormal conceptions. PGD for patients of advanced maternal age with an adequate number of embryos will improve their chances of childbirth via improved implantation and sustained gestation. PGD has also been used to help other specific groups of patients with high rates of chromosome abnormalities such as patients with recurrent spontaneous abortions, non-obstructive azoospermia, repeated IVF failure, and patients previous trisomic offspring. Recently, PGD has been performed using comparative genome hybridization, which counts all chromosomes; but time constraints require embryo cryopreservation, which reduces the potential of improved implantation