Insights into mechanisms causing the maternal age-induced decrease in oocyte quality

Female fertility declines with age, but the underlying mechanisms remain unclear. Here, we review the recent literature on the role of reactive oxygen species (ROS) within the oocytes. Specifically, ROS increase with age, damaging mitochondria and proteins important in oocyte maturation and meiosis. The damages to mitochondria impair ATP production. ATP levels in oocytes have been linked to successful completion of meiosis prior to ovulation and mediating the appropriate response to sperm binding. ROS also damage proteins important in DNA repair. Meiosis-specific homologs of DNA repair proteins have a critical role in recombination and preventing aneuploidy. Therefore, ROS-induced mitochondrial damage has widespread impacts on multiple aspects of oocyte quality. Some treatments are discussed which have shown to be effective in decreasing ROS-induced damage and lowering aneuploidy, providing hope to older women attempting to conceive. However, gaps in knowledge remain and require further investigation before more targeted treatments can be developed.