Basal Body Temperature (BBT) is an important part of fertility charting. The benefits of measuring your Basal Body Temperature each morning are:
1. You can see if you’re ovulating!
2. You can see WHEN you’re ovulating,
3. Once you’ve confirmed ovulation you’ll know when to expect your period (good for planning!)
4. You’ll be able to see if there are problems with your luteal phase that could make it hard for you to stay pregnant. (1)
So as you can see, Basal Body Temperature is a great tool. But it only works if you get an accurate reading! Here’s how to measure your BBT for the best results.
Step 1: Get a digital thermometer that is accurate to 1/10th of a degree Fahrenheit or 0.05 degrees Celsius.
Digital thermometers are usually accurate enough to catch the temperature shift - however, women who are not seeing a clear temperature shift using a regular thermometer may want to get a BBT thermometer, as they are slightly more accurate. The key is to get one that will get the job done, and that you like enough to actually use. If you hate the thing you won’t use it, so getting one you like is important (2).
Step 2: Keep it on your bedside table, on the side of the bed that you sleep on. Taking your temperature first thing in the morning is a habit that becomes second nature after a short while. Keeping your thermometer close at hand will make the habit much easier to create.
Step 3: When you wake up in the morning and are still laying in bed, (after at least 4 hours of good sleep) turn the thermometer on and put it in your mouth. It’s important to take your temperature as soon as you know you are awake and before doing anything else. Don’t do anything before taking your temp. This means no eating, no drinking, no getting up to pee, no smooching your sweetheart… all of those can raise or lower your BBT, and you need it to be accurate for best results (3).
Do your best to take your temp at the same time every day, if you take it earlier or later than usual this can affect your BBT, as temperatures tend to creep slightly higher the later you sleep.
Place the probe way back under your tongue, so the metal probe tip is as warm as possible. Now relax and wait till you hear it beep. And remember, don’t get up out of bed and measure your temperature in the bathroom. Once you’re out of bed your BBT is already altered.
Step 4: Once you hear the thermometer beep, take it out of your mouth and have a look at the temp. Remember it, write it down, or put it in your chart. Most thermometers have a Last Temperature recall function. This comes in handy if you sleep in a dark room and can’t see the temp on your thermometer, or you don’t have your glasses on, or whatever.
Step 5: Make sure to get that temp into your chart before the day is through.
1) Weschler, T. (2015). Taking Charge of Your Fertility: The Definitive Guide to Natural Birth Control, Pregnancy Achievement, and Reproductive Health pg 74.
2) Weschler, T. (2015). Taking Charge of Your Fertility: The Definitive Guide to Natural Birth Control, Pregnancy Achievement, and Reproductive Health pg 76.
3). Weschler, T. (2015). Taking Charge of Your Fertility: The Definitive Guide to Natural Birth Control, Pregnancy Achievement, and Reproductive Health pg 74.