Changes in sex hormones and their interactions are related to pain perception between different menstrual subphases.

Whether sex hormones are related to pain perception across the menstrual cycle is unclear. We examined changes in experimental pain perception in healthy young females between the early to midfollicular subphase (emF) and the midluteal subphase (mL) and explored the role of sex hormones. Sixty-six participants were involved in the study. We tested pressure pain, cold pain, ischemic pain, and needle pain, while at the same time we measured sex hormones levels in two menstrual subphases. Only the right ulna pressure test showed a significant reduction in pain threshold (PPTh3) during the mL. The absolute change of PPTh3 (PPTh3 - PPTh3) was related to the absolute change of prolactin. The relative change of the range of pain tolerance for pressure pain of the right ulna (RPT3) was related to the relative change of progesterone (P) and estradiol (E2) levels, and the interaction effects showed that at P ≤ 30, E2 was positively correlated with RPT3. The same, the relative change of pressure pain tolerance of the pulp of the middle finger on the right hand (PPTo4) was related to E2 and P, and the results of the interaction between E2 and P suggest that when E2 is ≤0.8, P is positively correlated with PPTo4. Two different formulas were applied in this study and showed inconsistent results. Most pain tests showed no difference between the two subphases of the menstrual cycle. Only the relative changes of the PPTo4 and RPT3 are related to the E2 and P, respectively, between menstrual subphases in an interactive way in healthy young women.