Background Oxidative stress (OS), defined as an imbalance between reactive oxygen species (ROS) and/or reactive nitrogen species (RNS) excessive production and antioxidant insufficient, has been suggested to be involved in the pathogenesis of poor ovarian response (POR). Growth hormone (GH) can function reduce OS in some types of cells. This study investigated whether GH can significantly improve OS and in vitro fertilization and embryo transfer (IVF-ET) outcomes in patients with POR.Methods This study enrolled 105 and 58 patients with and without POR (controls), respectively, diagnosed according to the Bologna criteria, who underwent conventional IVF-ET. Patients with POR were randomly assigned to two groups: POR-GH group: pretreatment with GH 4IU/d on day 2 of the previous menstrual cycle before IVF till the trigger day; POR-C group: no pretreatment. The markers of OS in follicle fluid (FF),reactive oxygen species (ROS) levels in granulosa cells (GC), and IVF outcomes of the patients were compared between the three groups.Result(s) The endometrial thickness on trigger day, number of cleaved embryos, higher quality embryos, the rates of implantation and clinical pregnancy were significantly increased in POR-GH group compared with POR-C group (P<0.05). Moreover, the FF malondialdehyde (MDA), total oxidant status (TOS), oxidative stress index (OSI) and ROS levels in GC were significantly higher,whereas superoxide dismutase (SOD) and total antioxidant capacity (TAC) were significantly lower in POR-C group compared with non-POR group (P<0.05). Furthermore, the FF TAC was significantly increased, whereas TOS, OSI and intracellular ROS levels were significantly reduced in POR-GH group compared with POR-C group (P<0.05).Conclusion(s) Pretreatment with GH alleviated OS and improved oocyte quality and IVF outcomes in patients with POR.Clinical Trial Registration: Chinese Clinical Trial Registry. ChiCTR1900021269. Registered 8 February 2019, http://www.chictr.org.cn/edit.aspx?pid=35837&htm=4.