WHEN IS YOUR SAFE PERIOD ?

     

When i hear how often girls get pregnant and do termination of pregnancies i wonder if they just want to or haven't thought of doing anything about it. So when is considered as safe period?
        First one should know the duration of her cycle which varies in individuals and is between 26-31 days and this is calculated from the first day of the last  menstrual bleeding to the first day of the present menstrual bleeding.