What is basal body temperature and when should I take it?
Your basal body temperature is the body temperature you can measure in the morning straight after waking up. It is the lowest temperature of the day and is therefore best used for comparison with other readings.
Your temperature rises throughout the day and peaks between 3 pm and 7 pm. It drops again at night – which is why you take your temperature in the morning before getting out of bed.
What does my basal body temperature tell me about my cycle?
After ovulation, the body releases progesterone. This hormone causes your body temperature to rise by 0.2 to 0.5 degrees Celsius.
On the basal body temperature chart, you’ll notice:
- A low phase in the first half of the cycle (before ovulation)
- A high phase in the second half of the cycle (after ovulation)
This rise in temperature is reliable proof that ovulation has taken place.
Which thermometer do I need?
You need a basal thermometer with:
- A measurement accuracy of 0.1 degrees
- Two decimal places (e.g. 36.57°C)
Recommended thermometers:
- Cyclotest Lady (digital)
- Geratherm basal (analogue)
- Selected Bluetooth thermometers – the ovolution app supports Bluetooth-enabled basal thermometers that automatically transmit the temperature
Standard clinical thermometers are not suitable as they do not measure accurately enough.
When and for how long should I take my temperature?
- When: In the morning, immediately after waking up – before getting out of bed, drinking or speaking
- For how long: 3 minutes, even if the thermometer beeps before then
- Important: Always take your temperature at the same time (± 30 minutes)
Where can I take my basal temperature?
You can take your temperature in three places:
- Rectally (bottom) – the most accurate method
- Vaginally
- Orally (mouth)
It’s important that you always take your temperature in the same place and with the same thermometer.
Analysing your basal body temperature with the ovolution app
The ovolution app automatically analyses your basal body temperature according to the Sensiplan® rules. You enter your readings – the app detects the rise in temperature and shows you your fertile and infertile days.