Many women who are deciding on fertility preservation (FP) are doing so at an advanced reproductive age, probably because this option has become available relatively recently, or due to the lack of awareness in young women about the depletion of the ovarian reserve and its effects on fertility. Recent studies show that age is the most powerful variable related to success after FP, which directly affects the number of oocytes vitrified, oocyte survival and cumulative live birth rate, with highest outcomes achieved by women aged ≤35y. Nonetheless, women in the ‘over 40’s’ can also succeed with their vitrified oocytes, although their probability of success is extremely low. An individualised treatment in older women, together with a comprehensive explanation of their situation to avoid creating false expectations, would be more advisable in order to set an age limit at 40 and deny the opportunity to these women. Likewise, women should be encouraged to decide on FP at young ages, when the chances are significantly higher.

The increasing survival rates of cancer patients [1] have encouraged many specialists to focus on the irreversible consequences of chemotherapy and radiotherapy. Chemotherapy and radiotherapy treatment for cancer or other pathologies have resulted in improved survival rates, but these treatments may also lead to sterility [2]. The increasing success of oncological treatments means it is now even more crucial to implement procedures aimed at preserving fertility.

Similar to cancer patients, there are some non-oncological conditions currently treated with gonadotoxic agents, such as patients with autoimmune disorders or some chromosomal abnormalities that can lead to ovarian failure. There are also other situations where a woman may benefit from fertility preservation procedures, such as women with severe or recurrent endometriosis or women who electively postpone conception [3].

Survival rates after cancer have increased significantly in recent decades; however, these treatments also have drawbacks, and patients (or parents in the case of children) must be informed of the long-term side effects of oncological treatments and the possible options for preserving the fertility of these patients. It is important to set out clearly the possible risks of developing ovarian failure or azoospermia with oncological treatments. These will depend on the age of the patients and on the type, dose and duration of chemotherapy, and on the field, dose and duration of radiotherapy.