Written by Nathalie Daudet
Every single month, naturally cycling women experience a wide range of hormonal events with ovulation being the peak of menstrual cycle hormonal activity. Many women are unaware of the cyclical rise and fall of hormones unless they’re charting their cycle. Using a basal body thermometer is one way of becoming in tune with the hormonal events that happen every month, by letting you peek through a window into your body’s inner rhythms.
What is Basal Body Temperature?
Your body’s lowest body temperature attained during rest is called your basal body temperature. In the pre-ovulatory phase of your cycle, your basal body temperature will be within a certain range for you. Once ovulation occurs, the presence of progesterone will increase your basal body temperature very slightly - by about 0.2C/0.4F. By tracking basal body temperature every day, we are able to observe this increase in temperature and narrow down the window of ovulation.
A basal body thermometer will be more sensitive than a fever thermometer, and will register to a more precise degree measure than a fever thermometer. To get an accurate basal body temperature reading with an oral basal body thermometer there are several requirements to ensure a good reading:
- Take your temperature at the same time each day, before getting out of bed
- Ensure you have at least 3 hours of consecutive sleep before taking a reading
- You can take an oral temperature under the “pocket” of your tongue
- You can also take your temperature vaginally, as long as you stick with the same method for your entire cycle
What Can Impact a Basal Body Thermometer Temperature Reading?
Keep track of factors that may interfere with an accurate reading. You can still track ovulation even with temperatures missing from your chart. If you think that you have a temperature that is disturbed, you can exclude that one temperature.
Here are a list of possible things that may increase or decrease your temperature. Note that not everyone may find these things disturb their temperature, it’s important to note which ones impact you!
- Drinking alcohol the night before
- Sleeping in a colder/warmer room than normal, or using a heating pad or blanket
- Temping significantly earlier or later than your regular time
- Time changes or daylight savings time
- Having a fever
- A restless sleep, that doesn’t allow you for three consecutive hours of sleep
There are situations that make it challenging to get an accurate reading, or to wake up at the same time each day. These include working night shifts, having young children, frequent travel, or an inconsistent wake up schedule. For these situations I recommend Tempdrop, which will allow you to get an accurate reading even with broken sleep, waking up at different times, variable environmental temperature and more. Tempdrop is worn all night long and excludes outside “noise” that can interfere with a reliable temperature reading.
What Do I Do With My Temperature Reading?
You can chart your basal body temperature on a charting app or on a paper chart, as long as it allows you to mark on a chart with .1 degree increments. You may prefer to chart in either Fahrenheit or Celsius, depending on your preference. Whether you are avoiding pregnancy or wanting to get pregnant, learning a method of fertility awareness will allow you to interpret your basal body temperature and how it relates to ovulation.
But Wait, There’s More to Basal Body Thermometers!
Basal body temperature is one piece of the charting puzzle. In the symptothermal fertility awareness method, we track both basal body temperature and cervical mucus. Tracking basal body temperature will give you a very clear picture of when ovulation has happened after the fact. Pairing it with cervical mucus will give you insights into when ovulation is approaching, which we can’t determine with basal body temperature.
For both conceiving and avoiding pregnancy, cervical mucus is an important thing to track. Be wary of apps or devices that claim to do the charting for you with basal body temperature alone. This is not an effective way to manage your fertility - as you are missing information prior to ovulation occurring.
Have I convinced you to track your basal body temperature yet? If you’re wanting to dive even deeper into understanding what your temperatures have to say, check Tempdrop's free Starter Guide to Fertility Awareness.
Nathalie Daudet is a social worker and FEMM instructor based in Winnipeg, Canada. She discovered fertility awareness after searching high and low for a non-hormonal method of birth control. After learning the magic of fertility awareness and the gift of body literacy, she decided to pursue formal fertility awareness training and share the knowledge of fertility awareness with women looking for a natural birth control option. Fertility Awareness Project is the hub for Nathalie’s FEMM classes in both group and individual formats, online and in person in Winnipeg. If you love this post and would like to thank Nathalie, shop Tempdrop with Nathalie's unique referral link.