Basal Body Temperature Chart (Symptothermal Method)

Anai Rhoads's picture

by Anai Rhoads

A basal body thermometer (BBT) is an ultra sensitive thermometer that tracks your body's exact temperature. A digital thermometer is your best bet. Each thermometer kit comes with a blank graph. These graphs may have space for you to record Pre-menstrual Syndrome symptoms (PMS).

At the top of the graph are the days of your cycle from 1-40, but you add more days if you need to. (Check out Pregnancy.org's online, interactive Ovulation Charting Tool.)

Underneath each cycle day you write the month and actual calendar date. Vertically listed are temperatures from 99.4-97.0 degrees F. (In Canada, the readings would be in metric units, at from 37.4-36.1 degrees C.) Each morning, before you get out of bed, you will need to take your temperature orally (you can vaginally, but orally is more accurate) and chart it on the graph. The graph will not be accurate unless you take your temperature the same time every morning.

After ovulation, your temperature rises between 0.36 and 0.9 degrees F (0.2 and 0.5 degrees C). After doing about three charts, you should notice a very distinct pattern of ovulation, which will help you time future intercourses and tell you whether you are ovulating regularly. However, this method will not tell you when to have intercourse, since the temperature does not rise until after ovulation. Do not make the mistake of planning intercourse around this chart. The purpose of the chart is to help you plan future intercourses and assist you in observing your own unique fertility pattern.

If you want to know ahead of time when you are ovulating, then this method is not for you. Ovulation kits and monitors are ideal for pre-ovulation detection.

The next step is to have your doctor perform blood tests to check your hormonal levels, or do an endometrial biopsy, a test that determines whether you are ovulating or have a hormonal imbalance.

Guidelines for an Accurate BBT Chart

The book, Taking Charge of Your Fertility, by Toni Weschler explains, by charting body temperature, it is simple to tell when pregnancy has occurred -- and when there is danger of miscarriage. Taking Charge of Your Fertility also explains how to choose the sex of your baby by timing intercourse according to certain fertility signs. It also features thorough, easy-to-understand explanations of hormones, the menstrual cycle, and menopause, along with fertility tests and treatments and their long -- and short-term side effects, plus a topnotch resource section.

  • The first day of your menstrual flow is day 1 of your BBT chart. Do NOT include spotting prior to your period as day 1. Your temperature should drop when your menstrual flow starts. Record your temperature throughout your period. This information is important.
  • Make sure you note the actual day of the month in the space provided on your chart.
  • Use an oral, digital, basal body thermometer ONLY. A regular thermometer will NOT work.
  • Take your temperature each morning before you get out of bed. Place the thermometer under your tongue for at least 2-3 minutes.
  • Don't eat or drink anything before you take your temperature.
  • Record your temperature by using a dot, not an X or a checkmark.
  • Use a down-pointing arrow to indicate the days you had intercourse.
  • Record any premenstrual symptoms if there is space on the chart. Otherwise, use your symptom chart to help link a certain temperature to a symptom.
  • Note any special considerations like colds, illness or fever.
  • Change charts when you get your period again.

Finally, on one of your charts, record what you are eating, how much you are exercising, and whether you are under any unusual stress. Coffee, alcohol, dieting, exercise, and emotional stress all affect your menstrual cycle in some way.

Anai Rhoads is a medical and political researcher/writer with a particular interest in the sanctions on Iraq and the wider effect of racism's influence in the Middle East. A vegan since 2000, she is a dedicated supporter of activities which promote animal and human rights. Originally from Greece, she now resides in Virginia, USA with her husband and their two dogs, Bijou and Eva.

Copyright © Anai Rhoads. Permission to publish granted to Pregnancy.org, LLC.