This may be due to a number of varying factors. Including surgical, genetic / heredity issues, related to pharmaceuticals and/or other drugs. They may even be from unexplained etiologies, which means we just do not know why or where the primary cause of the diminished functions of the ovaries started. Diminished ovarian reserve is a decrease in the number of viable eggs available for conception. This lack is in general caused by aging ovaries. The inadequate number of viable eggs decreases the chances drastically of ensuring successful fertilization of the eggs by the semen. Ovaries can still work fine while having a diminished ovarian reserve. Mid 30’s women have approximately 25,000 at the inception of menopause that number drops to around 100.