What is Basal Body Temperature (BBT) Charting?

Basal Body Temperature (BBT) is a measurement of your resting body temperature taken every morning to detect hormone changes that occur during your menstrual cycle. These changes are recorded and graphed to obtain information about your menstrual cycle for you and your provider.

What does "basal body temperature" mean?

"Basal body temperature" is the lowest temperature a healthy person achieves in a day. This temperature is most accurate in the morning, before you get out of bed or engage in any physical activity.

How does measuring my body temperature predict ovulation?

Progesterone is a hormone released from the cells surrounding an ovulated egg in the ovary. Progesterone is not released if ovulation does not occur. A rise in progesterone one to two days after ovulation causes body temperature to increase slightly. By detecting a rise in body temperature, one can predict that ovulation has most likely just occurred.

Directions for BBT charting:

Temperature chart to use

Receive a BBT Chart from your provider.

Wait until the first day of your menstrual cycle (the first day you need to wear a pad or tampon).

Take your temperature orally.

Make sure to record your temperature every morning before you get out of bed or engage in any activity.

Try to record this temperature at the same time every morning and after at least 4 hours of good sleep.

Record this temperature on your BBT chart.

Indicate on chart days of: menstrual flow, intercourse, or where temperature may have changed due to a cold, the flu, a fever, or even a restless night.

You should eventually notice your temperature rise and stay elevated. If your temperature rises 0.4 of a degree and stays at this new level for 4 or more days, this probably indicates that you have ovulated. The increase in temperature is due to an increase in progesterone.

Bring your completed BBT charts to your infertility appointments.

What is the difference between a basal body thermometer and a "normal" thermometer?

Basal body temperature thermometers are similar to "normal" oral thermometers but have been marked in smaller degree increments to obtain a more precise temperature measurement.

What does a BBT Chart tell me?

A BBT chart will help you predict when you are going to ovulate during your next cycle. You can begin to plan having intercourse every 36 hours during this time. Begin two to three days before predicted temperature rise and continue 3 days after temperature rise.

What if I don’t notice a change in temperature?

Unfortunately, many women do not show this classic temperature pattern, making it difficult to predict ovulation accurately. This could also indicate that ovulation is not occurring.

What does a BBT chart tell my provider?

The BBT chart can help your provider determine whether you may be ovulating, if your cycles are regular, and the timing of the second half of your cycle (the luteal phase).