What is Basal Body Temperature Charting?

Basal Body Temperature Charting involves recording your temperature everyday, before you get out of bed.

Ostrogen is the dominant hormone in the first half of the cycle, and during this time your temperatures will be around 36.11 to 36.38.

After ovulation occurs, progesterone is released which causes a thermogenic shift your temperature will rise slightly to around 36.44 to 37 degrees.

This temperature change is very small, a rise is likely to be just .20 to .60 degrees Celsius, but three or more consistently high readings indicates ovulation has occurred.

Charting your temperature daily on a graph (or app with a graph function) allows us to see very clearly what your temperature is doing throughout your cycle.

Ideally, 3 or more months of charts are needed to make the best assessment, the more data the better the assessment can be!

What do you need to do to record your Basal Body Temperature?

Buy a digital thermometer, this doesn’t need to be expensive, we recommend this one a lot in clinic.

Every morning, immediately on waking while your body is still technically ‘at rest’ take your temperature and record it

Apps can be helpful, Kindara, is good and free or on paper, we have this lovely free one to download here.


What can Basal Body Temperature charting tell you about your cycle?

  • The number of days for your follicular phase and your luteal phase
  • Confirms ovulation
  • Can give you information about your progesterone levels and how well sustained they are during your luteal phase
  • Can show how well your thyroid is functioning


What can impact your Basal Body Temperature readings?

Here’s a list of things that could make it unreliable;

  • Medications
  • Getting fewer than 3 quality hours of sleep
  • Illness
  • Jetlag
  • Using an electric blanket
  • Drinking alcohol the night before
  • Stress

When to stop?

If it’s stressing you out and you’re finding the daily task is a reminder and another fertility stress please stop, this doesn’t work for everyone and there are other methods to record your temperatures including Ovusenue, TempDrop, Aura, which can be less stressful.

If you’d like to learn more have a listen to our podcast BBT Charting episode where we take you through the do’s and don’ts of BBT charting, alternatively Katy has this BBT workshop available to watch and keep for a fiver.

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