Figure 2. The curvilinear relationship between CPR and E₂ levels on hCG trigger day in two groups.

A nonlinear association between serum E₂ levels on hCG trigger day and CPR of patients in the cleavage group (A) and the blastocyst group (B). The red lines represent the smoothing curve fit between serum E₂ and CPR, and the blue lines represent the 95% confidence interval.