Can a sexually dimorphic index of prenatal hormonal exposure be used to examine cold pressor pain perception in men and women?

There is considerable evidence to suggest that important differences exist between men and women in their experience of pain. Research has now turned to determine what the mechanisms of such differences actually are. One potential explanation is the effect of sex hormones, especially those typically found in greater concentration within women, e.g., estrogen, progesterone. However, it is also possible that other hormones, such as testosterone may be important. The current study employed a non-invasive sexually dimorphic index (digit ratio) that is believed to reflect prenatal exposure to testosterone, and related this to the cold pressor pain experiences of 23 men and 27 healthy women. As expected, females had greater symmetry between the second and fourth digits, and also reported lower pain tolerance levels. Although some significant relationships were found between digit ratio/digit length and cold pressor pain reports they were relatively inconsistent. Furthermore, the main finding, that pain thresholds were positively related to digit ratio in women but not men, is somewhat inconsistent with predictions. The results are discussed in light of methods for investigating the effect of prenatal hormonal exposure on pain sensitivity in men and women.