BBT What?: Everything You Need to Know About BBT Charting and Fertility

Why BBT charting?

One of the keys to optimizing fertility is learning about your fertile window. This is the period of about 3-5 days where your chances of conception during a menstrual cycle are the highest. It also represents the optimum lifespan of the egg and the sperm. By recording daily temperatures on a Body Basal Temperature (BBT) chart, and honing in on when certain physical signs are present during your period, we are able to pinpoint this window.

The BBT temperature represents the lowest resting body temperature, usually achieved during sleep. It is taken daily upon waking and before any movement, so it is best to keep the chart and your thermometer by your bed. You can plot the temperatures later, as long as you record the reading while you are still. Each chart begins with day one of your cycle, which is the first day of real flow of your period.

Why is this important for your acupuncturist?

Your BBT chart can identify potentially challenged areas of your cycle. At the same time, these charts are a great way for you to see the progress of your acupuncture treatments. Throughout your treatments, you will notice a more consistent cycle overall, less anxiety, and lighter symptoms of PMS. At the end of a cycle, we discuss our progress and set goals for areas that could use improvement. This is also a part of my goal of working collaboratively with patients and it’s a good way for you to be an active participant in your health.

Best time to take a BBT temperature?

Due to the natural circadian rhythm of the body, the best time to take a BBT temperature is between 6-7 AM.  Part of this practice involves establishing consistent sleeping and waking times. This relatively small act alone allows your body to work more efficiently, which allows for regulated hormone production and signaling in the body. It is important to support your reproductive cycle with ample sleep. My recommendation is to go to bed before 10 PM.  

Tips to help you get starting on charting your BBT temperature:

  1. On your chart, note what time you take your temperature and track adjustments in a different color so they can be identified.

  2. Adjust your BBT by 0.1 degree for every 30 minutes difference in normal waking time up to a maximum adjustment of 0.5 degree.

  3. If you normally wake up at 6 AM and you had to wake up at 5 AM, your temperature would be adjusted by increasing it 0.2 degree.

  4. If you normally wake up at 6 AM and you slept until 8 AM, your temperature would be adjusted by decreasing it 0.4 degree.

  5. Remember to flag any adjustment on your BBT chart.

  6. Keep the thermometer by the bed to limit physical activity before taking your temperature.

  7. Aim to get a good night’s sleep. Your basal body temperature should be taken with a minimum of four hours of relatively uninterrupted sleep. Interrupted sleep affects the pituitary gland, which regulates reproductive hormones and influences your BBT. If your night’s sleep was restless or interrupted, your temperature during the first half of a menstrual cycle will often be higher, and will drop during the second half of the cycle.

  8. If you have to get up to urinate during the night, take your temperature before you get up. When you wake up in the morning, take the temperature again to record the variance in temperature.

Factors that can influence the accuracy of the BBT reading:

  • Mouth breathing or snoring

  • Alcohol consumption

  • Traveling to a different time zone

  • Drugs that reduce fever, such as acetaminophen and ibuprofen

  • Long term use of anti-inflammatories or sleeping aids

  • The battery life in a digital thermometer

Key emotional symptoms to track throughout your BBT charting:

  • Irritability and Mood Swings (Liver meridian)

  • Anxiety and Nervousness (Heart meridian)

  • Depression and forgetfulness (Kidney meridian)

  • Crying and lack of confidence (Lung meridian)

  • Confusion (phlegm and dampness)

Key physical aspects to track during your cycle:

  • Insomnia and heart palpitations (heart)

  • Craving sweets and carbohydrates (spleen)

  • Increased appetite (heat). Progesterone is very warming

  • Breast tenderness (blood stasis)

  • Dull or achy back pain (kidney depletion)

  • Sharp or intense back pain (blood stasis)