If you mean as a way of birth control this is highly unreliable and
does not prevent the spread of STDs. The girl monitors her menstrual
cycle for several months and if it is in the region of 26-30 days and
almost exactly the same time each cycle then using the calendar method
SLIGHTLY reduces the chance of conception on days 1-8 of the cycle. I
can't stress how unreliable this is, using a condom is much much better
and also prevents against STDs.
does not prevent the spread of STDs. The girl monitors her menstrual
cycle for several months and if it is in the region of 26-30 days and
almost exactly the same time each cycle then using the calendar method
SLIGHTLY reduces the chance of conception on days 1-8 of the cycle. I
can't stress how unreliable this is, using a condom is much much better
and also prevents against STDs.