The rhythm method is the least precise of the fertility awareness methods and works best in women who have very regular twenty-eight day menstrual cycles. This method involves charting the beginning and ending of periods for at least six months to determine when ovulation occurs and then using that information to predict fertile days. Day one of the menstrual cycle is the first day of a woman's period. The last day of the cycle is the day before the start of her next period. For women who have regular 28 day cycles, fertile days usually range from the ninth through eighteenth day of their cycles.
Women using the temperature method can use any ordinary thermometer to determine their temperature.
To correctly use this method, a woman must take her temperature every morning before getting up after at least three hours of sleep, and then record it on a chart. Usually temperature readings will be lower before ovulation and then remain elevated after ovulation until the next cycle begins. For some women, waiting to have intercourse for about three days after this rise in temperature will successfully avoid fertile days and prevent pregnancy. The cervical mucus method requires careful daily examination of a woman's vaginal secretions to look for specific changes in their amount, texture and appearance. These findings are recorded daily on a chart.