In vitro maturation (IVM) of oocytes retrieved at germinal vesicle stage, followed by vitrification of mature oocytes, has emerged as a fertility preservation (FP) option. This technique was first developed for patients with polycystic ovarian syndrome. In this population, providing LH activity prior to oocyte collection has been associated with better IVM outcomes. However, the benefit of this treatment in normo-ovulatory breast cancer (BC) patients undergoing IVM for FP purpose has never been investigated. To assess if the absence of therapeutic intervention prior to oocyte retrieval for IVM modifies IVM outcomes in BC patients undergoing urgent FP, we performed a non-inferiority, randomized controlled trial. The main outcome was the total number of mature oocytes obtained and cryopreserved after IVM. A total of 172 normo-ovulatory women, suffering from BC, 18 to 39 years of age received no injection or a subcutaneous injection of hCG or GnRH agonist (GnRHa) 36 h before oocytes retrieval according to randomized allocation. The total number of cryopreserved oocytes were 5.1 ± 3.8, 5.4 ± 3.8, and 6.0 ± 4.2 oocytes, respectively in the without, hCG and GnRHa groups. Mean differences were not significant between the three groups (− 0.5; CI 97.5% [− 2.03:1.02] and − 0.22; CI 97.5% [− 1.75:1.32], respectively). Intention to treat analyses failed to show non-inferiority in the “without injection group” in comparison with hCG or GnRHa groups. Our results are not conclusive enough to modify our practices and to stop administering hCG or GnRHa before IVM cycles for FP. The study was retrospectively registered to clinical trial (ID NCT03954197) in May 2019.