Decreased fertility is a consequence of maternal aging in humans and domestic species. Studies of older females identify numerous responsible factors, including decreased ovarian reserve, altered hormone secretion patterns, diminished ability of oocytes to support early embryo development, and a sub-optimal uterine environment. Coincidently, there is a trend for women to reproduce later in life. Ovarian stimulation has become the method of choice to combat reduced fertility, to overcome reproductive diseases and disorders, or to simply improve reproductive outcomes. Despite ovarian stimulation regimens being employed, responses and success rates are variable, as increasing maternal age and ovarian stimulation regimens result in a sub-optimal follicular environment, which can comprise oocyte viability and thus the successful establishment of a pregnancy. Determining the relative influence or interdependence of maternal age and stimulation regimens, as well as the underlying cause of infertility, is complicated however, especially in humans. To date, individual studies have focussed on either the genetic contribution, follicular hormone or metabolite concentrations, or cumulus or oocyte gene expression but not all these factors collectively within the same cohort. Equally, no study has investigated mitochondrial DNA (mtDNA) heteroplasmy in individual oocytes that may explain metabolic dysfunction, and little is known about whether the oocyte alters mtDNA copy numbers, mutations and deletions, following ageing or ovarian stimulation. To gain a more comprehensive understanding of these interactions, my research lab has examined the effects of maternal age and ovarian stimulation regimens on all the aforementioned follicular characteristics using a novel bovine model. We have utilised these data to establish diagnostic oocyte quality markers and to postulate potential new approaches that may avoid negative effects on the follicular environment and improve upon the current ovarian stimulation methods. Use of this knowledge may therefore provide approaches to optimise the fertility and success rates of older females.