Effects of sex, phase of the menstrual cycle and gonadal hormones on pain in healthy humans.

Sex differences in pain have been noted; women typically report more pain than men. Gonadal hormones may influence pain reports, and, moreover, such hormones may help to explain sex differences and menstrual cycle differences in pain. This study measured venipuncture and intravenous catherization pain during the follicular and luteal phases of the menstrual cycle in regularly menstruating women. Pain was also assessed in a group of men. Pain ratings were higher in women than men. In women, pain ratings did not differ between the follicular and luteal phases. Estradiol and progesterone increased from follicular to luteal phases. Within-phase analyses revealed that pain ratings were positively correlated with estradiol and progesterone during the luteal phase. Moreover, increases in estradiol and progesterone across the menstrual cycle were positively correlated with increases in pain. These findings suggest that variations in gonadal hormones during the menstrual cycle influence the experience of pain in healthy women.