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 EMI tissues from the patients with EXB had significantly higher fibrotic content but significantly lower immunostaining levels of HIF‐1α, COX‐2, EP2, and EP4 (all p‐values<0.0004; all R2's ≥ 0.42). The gene discussed is PTGER4; the disease is endometriosis.