Clinical practice guideline for female fertility preservation.

Introduction: Female fertility preservation (FFP) has become a clinical priority because gonadotoxic therapies for cancer and benign diseases are increasingly common and may cause irreversible ovarian failure. The current clinical practice guideline provides evidence-based recommendations on fertility assessment, oocyte/embryo cryopreservation, and ovarian tissue cryopreservation and transplantation for women at risk of iatrogenic infertility. Methods: This guideline was developed in accordance with the WHO Handbook for Guideline Development. A multidisciplinary Guideline Development Group (GDG) formulated nine key clinical questions in the field of FFP, and Cochrane-standard systematic reviews were conducted for each question. The certainty of the evidence was assessed using the GRADE approach, with critical outcomes including live birth, clinical pregnancy, time to pregnancy, treatment-related delays in oncotherapy, and severe ovarian hyperstimulation syndrome (OHSS). Recommendations were formulated by the GDG through the GRADE Evidence-to-Decision framework. Results and discussion: The GDG agreed on nine recommendations tailored to the Chinese clinical practice environment. When cancer treatment must start within two weeks, a random-start stimulation protocol is conditionally endorsed; pooled data show only one extra mature oocyte, but the time saved outweighs the marginal gonadotrophin increase. Letrozole co-administration is strongly recommended because it restrains oestradiol without reducing yield and may lessen OHSS risk in hormone-sensitive tumours. For ovarian tissue cryopreservation, slow freezing and vitrification are deemed equivalent in the absence of comparative trials; institutional capacity dictates the choice. Concurrent GnRH-agonist during chemotherapy is strongly advised across seventeen RCTs and improves subsequent live birth. Oocyte cryopreservation is weakly preferred to tissue for sexually mature women on the basis of higher cumulative pregnancy and lower morbidity, while ovarian tissue cryopreservation remains the default when stimulation is impossible. Baseline fertility evaluation should combine age, AMH and AFC; no single marker is superior, yet together they refine counselling. Orthotopic transplantation is strongly favoured over heterotopic grafting because published live births are almost exclusively pelvic. Finally, ovarian cortical fragments should undergo routine histopathology, augmented-according to metastatic risk-by immunohistochemistry, PCR or murine xenograft; tissue harbouring malignant cells is usually withheld from re-implantation.