couple snuggling in bedOne of the best ways to monitor your menstrual cycle is to take your temperature with an oral thermometer at the same time every morning and record this information on a temperature graph—a reading that is known as your basal body temperature (BBT) chart or resting temperature chart.

If you are ovulating normally, your temperature might drop slightly just before ovulation and then shoot up once you have ovulated. Just remember: this is not a reliable indication of impending ovulation. Not every woman experiences this dip in temperature and even if you do, by the time you’ve “dropped” and your temperature has rebounded, baby-makin’ season has passed. Your temperature will usually range between 97.0 and 97.5 degrees Fahrenheit before ovulation, and 97.6 and 98.6 after ovulation. If you are already pregnant, your temperature will remain elevated for all nine months. If you’re not pregnant, your temperature will begin to drop close to or on the day your period starts, as the levels of progesterone in your body decrease.

You will want to record when you had intercourse on your chart.

Many women find it useful to include some other types of information on their BBT charts, as well: changes to their daily routines that may have affected their temperature on a particular morning, a cold or fever, consumption of alcohol the night before, getting less than three consecutive hours of sleep, taking your temperature at a significantly different time than usual, or sleeping under an electric blanket if you don’t usually do so can throw your readings off.

Although BBT charts are a source of very useful information, they aren’t a completely useful tool for everyone. Some women who are ovulating normally don’t experience the temperature rise prior to ovulation—their basal body temperature remains constant throughout their menstrual cycle. These women often find it easier to monitor their cervical mucus, as well.