Figure 4.

Comparison of SS levels at different time points between the 2 groups ($\overline{x}\pm s$). The abscissa represents T0, T1, T2, and T3, while the ordinate represents the SS level. The SS levels at T0, T1, T2, and T3 in the study group were 23.56±3.17, 29.62±4.51, 32.46±4.18, and 45.72±4.57 pg/mL, respectively. The SS levels at T0, T1, T2, and T3 in the reference group were 23.63±3.21, 26.02±4.31, 27.11±3.91, and 35.61±4.21 pg/mL, respectively. *, indicates that there were significant differences in the SS levels at T1 between the 2 groups (t=4.544; P<0.000). **, indicates that there were significant differences in the SS levels at T2 between the 2 groups (t=7.360; P=0.000). ***, indicates that there were significant differences in the SS levels at T3 between the 2 groups (t=12.812; P=0.000).