General duration of the menstrual cycle

Question

Write down the general duration of the menstrual cycle? Also how does the calendar contraceptive scheme work?

Answer 1

The general duration of the menstrual cycle is about 28 days but it may vary among different women or in different cycles of  same woman.  In the calendar contraceptive scheme the date n-14 (i.e. n minus 14) is taken concerning ‘n’ the number of days of normal menstrual cycle of the woman (normally n=28). The safety margin +3 or –3 refers to days approximately n-14 so intercourse ought to be avoided to prevent pregnancy. (This scheme isn’t exempt from failures. A doctor should always be consulted prior relying on whichever contraceptive method.)