This method is sometimes called the ovulation method . Chart your menstrual cycles on a calendar. You may be able to predict ovulation if your periods are the same every month and if you chart many cycles before attempting to predict when you will ovulate. It will be more difficult to predict the day of ovulation if your cycle length varies from month to month. Of 100 women using periodic abstinence , about 25 will become pregnant during the first year of typical use.
Perfect use can give better results.
Nine women will become pregnant with perfect use of the calendar method . Pregnancy rates generally are higher for single women who use these methods. Neither periodic abstinence nor FAMs provide protection against sexually transmitted infections. There are no medical or hormonal side effects. Calendars, thermometers, and charts are easy to get.