Evaluating the Impact of Female Factors on Specific Stages of Early Embryo Development: A Retrospective Analysis of 1372 IVF Cycles

Purpose: To ascertain whether female factors uniformly impact the entire spectrum of early embryo development during in vitro fertilization (IVF) treatments or if their influence is confined to specific stages. Methods: A retrospective observational study. Univariate and multivariate logistic regression analyses were performed to identify the influence of female factors on different stages of embryo development. Results: Significant differences in female age, AMH, AFC, and gonadotropin (Gn) dose were observed across the five groups ( p < 0.001). When comparing the lowest (Group A) and highest (Group E) performance groups, female age (OR=1.18), AMH (OR=0.40), AFC (OR=0.86), and initial Gn dose (OR=0.99) were independent predictors of early embryo development (all p < 0.05). In contrast, when comparing intermediate (Group D) and high (Group E) performers, factors independently associated with high-quality day-5 blastocyst formation included female age (OR=1.08), AMH (OR=0.89), AFC (OR=0.91), and LH/FSH ratio (OR=1.37) (all p < 0.05). Conclusion: Female factors exert stage-specific effects on early embryo development in IVF, supporting the need for individualized clinical strategies. Notably, an optimal LH/FSH ratio was associated with improved blastocyst quality, although prospective studies are warranted to validate this threshold and its clinical applicability.