Everyone knows there is a big difference between the life expectancy of women versus men. Statistics show women live about four to five years longer than those of the opposite sex.

A researcher from the Netherlands suggests that you can chalk it all up to our menstrual cycle during the key years of our lives.

According to his research, the hormone endogenous estradiol, which is released during the menstrual cycle and in pregnancy, “provokes marked cardiovascular changes.” It increases the cardiac output to a degree that mimics the effect of cardio exercise.

In other words, this researcher says having a period year in and year out, over time, creates a stronger heart — and that may be one reason why women across the globe typically outlive their male mates.