calendar method of birth control

calendar method of birth control
    n 1: natural family planning in which ovulation is assumed to
         occur 14 days before the onset of a period (the fertile
         period would be assumed to extend from day 10 through day
         18 of her cycle) [syn: {rhythm method of birth control},
         {rhythm method}, {rhythm}, {calendar method of birth
         control}, {calendar method}]