PTGER4 and adenomyosis: With the only exception for HIF‐1α (p > 0.10), in which there was no significant difference between the two groups of patients, multiple linear regression analyses incorporating group identity (MHB vs. EXB), age, parity, menstrual phase, uterine size, type of adenomyosis, co‐occurrence of ovarian endometrioma, deep endometriosis, or uterine fibroids and use of iron supplements confirmed that endometrial tissues from the patients with EXB had significantly higher fibrotic content but significantly lower immunostaining levels of COX‐2, EP2, and EP4 (all p‐values ≤0.041; all R2 ≥ 0.22).