Age has a negative effect on a woman's ovarian reserve which means that the older she gets the less eggs she has available. It is not possible to increase her egg reserve. Therefore, the ovarian reserve will inevitably decrease over time until it becomes zero when a woman reaches menopause.
However, the decrease in ovarian reserve can be accelerated by certain external agents, such as surgery, chemotherapy or radiotherapy, among others. For this reason, all these factors must be taken into account if she wants to get pregnant.