Fig. 4

Serum progesterone concentrations (a) in normal women at different stages of the menstrual cycle. a,b different superscript letters indicate significant differences between groups (p < 0.05). Correlation of serum miRNA-23a and miRNA-23b expression with progesterone in normal women (a and b), in normal women at different stages of the menstrual cycle (c–k), and in PCOS patients (l and m). The scatter plots showed no significant correlation coefficients (p > 0.05)