Lesson 9 – Factors that Can Affect the Accuracy of Your BBTs


  • Learn what factors can influence BBT
  • Learn how these factors can affect your charting efforts

Major Points:

There are certain factors that can affect the accuracy of your basal body temperature (BBT). These factors should be noted in your chart data.

  • Certain diet, lifestyle, and health factors can influence the accuracy of your BBT.
  • If one or more of these factors apply to you, charting is still possible.
  • Recognizing factors that could influence your BBT chart is important to ensure that your data is accurate.

Factors that can affect your basal body temperature

Charting your basal body temperature (BBT) is an excellent way to detect ovulation and increase your odds of conception. However, certain factors can influence your BBT and therefore skew your results.

When you face certain factors that could affect your basal body temperature, it’s important to make a note in your chart. While inconsistencies in your chart do not always make recording BBT impossible, it can present some challenges.  Even when there are challenging factors on a going basis, reading your chart is still possible.

The following factors may influence your BBT:

  • Fever, illness, or infection (e.g. sore throat, cold, flu)
  • Alcohol consumption (especially in large quantities)
  • Medications and drugs
  • Smoking (consider quitting before becoming pregnant)
  • Physical or emotional stress
  • Excitement
  • Jet lag, change in climate, or other bodily changes due to traveling
  • Sleep disturbances (poor sleep, insomnia, night-waking, etc.)
  • Use of a heating pad or electric blanket
  • Breastfeeding
  • Change in temperature of your bedroom

How you take your BBT can also greatly influence your results, especially if you are inconsistent with your routine. It’s ideal to take your temperature as soon as you wake to avoid a spike in temperature due to movement. To increase your odds of an accurate reading, take your temperature immediately after waking and before getting out of bed to use the bathroom and before eating or drinking. It’s best to take your temperature at the same time daily.

If you’re trying to conceive or simply want to detect ovulation, your basal body temperature can tell you a lot about your cycle. However, it’s important to be aware of certain factors that can alter your results. Once you’ve settled on a morning routine, checking your BBT will become second nature.