Aims and background: The optimal size of the leading follicle at which ovulation trigger should be given in the gonadotropin-releasing hormone (GnRH) antagonist protocol has not been validated yet. We carried out this study to assess the role of delaying ovulation triggering, with the leading follicle beyond 20 mm, in enabling the maturation of medium-sized follicles during controlled ovarian stimulation (COS). Materials and methods: A total of 427 infertile women between the age-group 21 and 45 years, undergoing COS with flexible GnRH antagonist protocol were included, and before stimulation, they were categorized into three groups, namely predicted poor (group I), normal (group II), and hyper (group III) responders. On the day of the trigger, all three groups were further split into two subgroups based on the leading follicle diameter (subgroup A: <20 mm and subgroup B: ≥20 mm), and assisted reproductive technology (ART) outcomes were analyzed between the subgroups. Results: The number of oocytes retrieved [6.8 ± 3.9 vs 4.0 ± 2.7, 95% confidence interval (CI): 1.10–4.44; p = 0.001], the number of metaphase II oocytes among them (4.6 ± 3.1 vs 2.8 ± 1.9; 95% CI: 0.48–3.06; p = 0.008) and the resultant total number of embryos available for freezing (3.5 ± 2.6 vs 2.2 ± 1.7; 95% CI: 0.17–2.41; p = 0.024) and the number of grade I embryos (2.0 ± 1.9 vs 1.1 ± 1.4; 95% CI: 0.15–1.77; p = 0.021) were significantly increased in group IB when compared to group IA. The cycle outcomes were marginally improved, though not significant, in subgroups IIB and IIIB when compared to subgroups IIA and IIIA, respectively. Oocyte maturation rate and fertilization rate were comparable between the subgroups. Conclusion: Delaying the trigger for oocyte maturation has a role in improving the outcomes in poor responders. Clinical significance: Delaying the ovulation trigger in enabling the maturation of medium-sized follicles leads to clinically better yield of oocytes and good quality embryos in predicted poor responders.