To Change or Not to Change? The Benefit of Ivf Protocol Modification in a Subsequent Cycle

Objective: To evaluate whether a protocol modification or not between a first and second IVF cycle was associated with improved clinical outcomes. Design: A retrospective longitudinal cohort study of patient charts that compared first and second IVF cycles. Materials and Methods: A total of 259 patients who underwent two consecutive IVF cycles between Jan 1, 2020 and Dec 31, 2025 were included in this study. Patients (n=213) who had a stimulation protocol assessment and chart review resulting in a treatment change (Change) were compared with a cohort (n=46) who underwent repeat IVF cycles without any change (No Change) in stimulation protocol. Cycle outcomes included: # of oocytes retrieved, fertilization rate, # of blastocysts, and blastocyst utilization rate (BUR). Descriptive statistics were calculated as means ± standard deviation. First- and second-cycle outcomes were compared using t-tests, with p < 0.05 considered statistically significant. Results: Mean patient age were similar between cycles and groups. Following protocol modification, the mean number of oocytes retrieved increased significantly from 9.45 ± 5.94 to 11.19 ± 6.71 (p=0.005), representing an 18.4% improvement in oocyte yield. Although not statistically significant (p=0.134), fertilization rate increased slightly from 53.2 ± 25.0% to 56.8 ± 23.6%. Mean blastocyst yield improved over 50% from 1.92 ± 1.90 to 2.89 ± 2.77 (p<0.001). BUR also increased significantly from 34.0 ± 28.1% to 41.2 ± 28.6% (p=0.012) in a cycle after a protocol change. In contrast, no clinical outcome improvement(s) were observed among patients in the No Change Group. Conclusions: This study demonstrates the benefit of protocol modification for a second ovarian stimulation cycle. These findings support reassessing and personalizing stimulation strategies after an initial IVF response to optimize subsequent cycle outcomes and treatment efficiency.