Sex differences in cardiovascular stress responses: modulation as a function of menstrual cycle phases.

An experiment was conducted to study the effects of two laboratory stresses (unsignalled shock-avoidance reaction time and cold pressor tasks) on cardiovascular responses of young adult women during the follicular or the luteal phases of the menstrual cycle. A comparison group of male subjects, matched for family history of hypertension and for time between stress and rest sessions, was also tested. Results showed reduced cardiovascular responsiveness to the reaction time task (heart rate and blood pressure) for the women in the follicular phase of their cycle as compared with those in the luteal phase or with the males. Cardiovascular hyperresponsivity to this task has been previously related to familial history of hypertension. No differential changes were observed during the cold pressor test. These results are discussed in terms of possible hormonal effects on blood pressure regulation, and with respect to methodological considerations for assessing stress reactivity among women.