In vitro activation of cryopreserved ovarian tissue: A single-arm meta-analysis and systematic review

•Primordial follicles in premature ovarian failure (POF) patients are very difficult to be activated spontaneously.•So mature oocytes are difficult to be obtained for in vitro fertilization in premature ovarian failure (POF) patients.•For ovarian disorder patients, in vitro activation can be a promising option for fertility preservation.•According to our results, drug-free in vitro activation of primordial follicles is a new potential treatment comparison with drug-induced activation.