How It Is Done continued...
Take your temperature every morning for several months just after you wake up. Do it before eating, drinking, or doing any other activity. Use a special ovulation thermometer or digital thermometer that shows tenths (0.1) of a degree. Your temperature may be taken orally or rectally, but be sure to use the same location and the same thermometer each time. Leave the thermometer in place for a full 5 minutes. Record your temperature, then clean the thermometer and put it away. Any activity can change your basal temperature. Record your temperature on a chart or graph. Use a tracking chart with either Fahrenheit temperatures(What is a PDF document?) or Celsius temperatures(What is a PDF document?) to keep track of your temperature. Ovulation usually causes your BBT to rise by 0.4°F (0.2°C) and to stay high for over a week.
If you want to become pregnant, have sex every day or every other day from your first fertile day until 3 days after your BBT rises.
If you do not want to become pregnant, do not have sex or be sure to use another method of birth control from the end of your menstrual period until 3 days after ovulation. After your temperature rises and stays high for 3 full days, your fertile days will be over. Your temperature on these 3 days should stay higher than on any of the other days in that cycle.
Cervical mucus method (Billings method)
Each day, put one finger into your vagina and record the amount, color, and thickness (or thinness) of the mucus. Test the "stretchiness" of the mucus by putting a drop of it between your finger and thumb. Spread your finger and thumb apart and see if the mucus stretches.
After your period, you will not have much cervical mucus, and it is thick, cloudy, and sticky. Just before and during ovulation, you will have more cervical mucus and it is thin, clear, and stringy. It may stretch about 1 in. (2.5 cm) before it breaks.