BBT charting for fertility; why, how and when to stop
A basal body chart is record of your daily resting body temperature. It’s essentially a cool little tool that gives both your practitioner and you all sorts of information about your body as you move through your cycle.
We love it when our patients record their daily BBT
It helps you:
Recording data over a few cycles can help you understand your body and help better predict ovulation and likely fertile days. Yes yes, the romance is there, the chemistry is still alive, etc etc, but from clinical experience, less conception sex is generally a welcome relief.
It helps us:
A BBT chart can help us see all sorts of things – it can confirm ovulation has occurred and give us a very good indication of when. It helps us decide what herbs to give you and when to change formulas, how you are responding to a treatment, how your body responds to different stressors or lifestyle factors, if your progesterone is holding up, and even reveal undiagnosed, or subclinical pathology like this:
True story: I had a patient who was TTC for nearly 8 cycles. She had been tracking her temperature for 2 cycles. From this data alone, we could see her thyroid was likely under functioning. Further investigation, tweaks from her naturopath, 2 cycles with us at The Fertility Suite, her temps changed and this story has a happy ending.
A BBT thermometer is specific to decimal places.
Heres how it works
A BBT chart tracks very slight changes in your temperature.
Estrogen and progesterone fluctuate throughout the menstrual cycle. Estrogen is the dominant hormone in the first half of the cycle, it is comparatively yin and cooler. When estrogen is dominant, your temperature will be around 36.11 to 36.38.
After ovulation occurs, progesterone is released causing a rapid rise in progesterone, a more yang and warming hormone. When progesterone is more dominant, 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.
Here's how you do it:
You will need to purchase a BBT thermometer. This differs from a regular thermometer in that it is very specific – temperature needs to be recorded to two decimal places. Consistency is key! Every morning, immediately on waking while your body is still technically ‘at rest’ take your temperature and record it on your graph or in an app. Mark it down on your chart and connect the dots to make a graph.
Temps need to be taken and recorded immediately on waking
Our temperature can be incredibly fickle. Here’s a list of things that could make it unreliable;
Medications
Getting fewer than 3 quality hours of sleep
Having a fever
Jetlag
Using an electric blanket
Drinking alcohol the night before
Stress
Airconditioning
The weather
Looking for patterns - add a cover line
I like adding a cover line – it helps us to see a trend as oppose to individual readings, and gives a clear idea of a temperature shift. Some apps will do it automatically. It sounds a little confusing but is easy once you have done it once.
When you see a temperature increase of .2 to .6 celcius check that it has been high for 3 consecutive readings. This is the ‘sustained temperature rise’
Find the temp prior to the sustained temperature rise
Including that temp, count back 5 temperatures
Find the highest of these five temperatures
Place a small mark just slightly above the highest reading
Draw a horizontal line - this is your cover line, and it’ll help you see patterns and and trends in your charts.
A biphasic chart confirms ovulation has occurred.
When to stop charting
Some women love charting. It you’re data oriented, or thrive on routine we can keep BBT charting until you become pregnant and then pick it up again later on in your life if you choose. But what if you kind of hate it? If you feel it is just another chore? We’d probably ask you to try BBT charting for 3 months. Sometime 3 months is enough time to see patterns or trends. If you hate it after this, take a break. If it makes your crazy, please just stop. We have other tools if we can use too. Sanity first.
To read more about identifying your fertile days, check out this article next.