It is interesting to note that
menstrual cramps can be measured by the pressure within the
uterus and the frequency and number of contractions. The average woman experiencing a normal menstrual period has low-pressure contractions, 15-30 second long, with 1-4 contractions per minute. A woman with menstrual cramps has contractions of a higher pressure (sometimes more than 5 times higher than her counterpart), over 90 seconds long, and often less than 15 seconds apart.