Approximately one in every seven pregnancies ends in miscarriage. Yet despite thorough evaluation, the etiology of recurrent miscarriage cannot be determined in at least 50% of cases. Approximately 0.6% of sperm from normal ejaculates possess aneuploid sets of chromosomes, although this incidence increases to 6% with disordered spermatogenesis, as reflected in severe oligospermia, and to 14% in nonobstructive azoospermia. Paternal aging affects the sperm epigenome, which potentially could impact embryonic development. These data raise the need for future investigation to confirm the role of spermatozoa in miscarriage.