Natural history of diminished ovarian reserve

There are two proposed models for oocyte endowment in females. Both fixed cell and stem cell models acknowledge the depletion of oocyte pool with female aging. The ovarian cortical tissue-based models suggest that there is a very high number of primordial follicle loss in early life from birth to puberty. After the age of 20 years, the average number of follicles lost decreases with the lowest level observed as women approach menopause. It is believed that there is no specific female age after which the oocyte loss accelerates further. Actually, clinical evidence suggests that the decline in ovarian reserve after the peak loss point of around the age of 20 years is followed by gradual loss over the years. As the ovarian reserve decreases further, the number of primordial follicles lost may also decrease. Individual variation in menopausal age may also provide some clues that diminished ovarian reserve (DOR) may be due to a shift of the primordial or nongrowing follicle depletion curve to earlier age, which can be due to many genetic and environmental factors yet to be determined. The decrease in oocyte quality in parallel to ovarian reserve decline with female aging may be skewed in younger females with DOR. Therefore, age may still dictate the quality of oocytes regardless of the ovarian reserve. It is still not clear if fertility patterns are associated with the longevity or if DOR is a direct reflection of general aging.