Follicular development dynamics, ovarian response, and reproductive outcomes among three recombinant FSH preparations: a single-center retrospective cohort study

Abstract Background Recombinant follicle-stimulating hormone (rFSH) preparations differ in their glycosylation profiles and pharmacological properties. However, whether these molecular differences influence follicular growth dynamics during controlled ovarian stimulation (COS) remains unclear. We compared follicular development, ovarian response, and reproductive outcomes among follitropin alfa, beta, and delta. Methods This retrospective cohort study included 329 women undergoing their first controlled ovarian stimulation cycle with follitropin alfa ( n = 151), beta ( n = 111), or delta ( n = 67). Primary outcomes were oocyte yield, mature oocyte yield, follicle-to-oocyte index (FOI) and follicle-to-mature oocyte index (FmOI). Secondary outcomes included follicular development, endocrine profiles, embryological outcomes, ovarian hyperstimulation syndrome, cumulative pregnancy rate, and cumulative live birth rate. Outcomes were compared using multivariable regression analyses or logistic regression analysis adjusted for age, anti-Müllerian hormone, and body weight. Results Follitropin alfa and beta showed broadly comparable ovarian responses and stimulation durations, whereas differences were observed in comparisons involving follitropin delta. Exploratory analyses revealed modest numerical trends toward higher oocyte yield and FOI and shorter stimulation duration with follitropin beta than with alfa, although these differences were not statistically significant after adjustment for multiple comparisons. Cumulative reproductive outcomes were comparable among the three groups. Conclusions Although reproductive outcomes were comparable among recombinant FSH preparations, differences in ovarian responsiveness were observed, with follitropin beta showing modest exploratory trends toward greater ovarian response and shorter stimulation duration. Despite the retrospective design and lack of an a priori power calculation, these findings highlight the potential value of follicular growth dynamics in individualized ovarian stimulation.