Are You Considering Charting Your BBT (Basal Body Temperature)?

Have you ever thought about charting your BBT? Are you not sure how? What is BBT exactly and what can it tell you about your body and your cycle??

BBT or Basal Body Temperature is a woman’s body temperature at rest. Due to hormonal activity, a woman’s resting temperature changes during her cycle. Lower temperatures indicate that ovulation has not yet occurred. Higher temperatures indicate a rise in progesterone, which signals the end of the fertile time.

Charting your BBT is pretty easy really. The basics of what you will be doing is taking your temperature each morning and plotting it on a temperature chart. (You can either do this manually on a chart, or there are many online charts that you can use by simple date entry. Many of the online charts are free and some offer advanced services for a minimal fee.) You are looking for a shift of at least .4 degrees Fahrenheit, after ovulation, to show a biphasic (showing low temperatures before ovulation in the follicular phase, and higher temps after ovulation, during the luteal phase. It can also be helpful to use ovulation predictor tests in conjunction with charting your BBT, to help narrow down the most fertile time during your cycle.

BBT Charting Guide and Tips:

1. Take your temp first thing in the morning before you get out of bed, or even speak. The less movement, the better. Put your thermometer right next to your bed, so that you can easily reach it. If you happen to use a glass thermometer, make sure to shake it down the night before. You do not have to use a BBT thermometer, but they are more accurate and only about a dollar or so more than a regular digital thermometer.
2. It is important to try to take your temp at the same time each day-or as close to the same time as possible. Setting an alarm is a great idea. Maybe you sleep later on the weekends but to get an accurate picture of your BBT, this is very important. Staying within half an hour on either side of your usual time is okay. So if you normally wake up at 7, taking your temp between 6:30 and 7:30 should still be pretty accurate. The normal variation is .2 degrees per hour, however all women are unique, so that can vary from woman to woman. It is lower if you take it earlier and higher if you take it later.
3. It is best to take your temp after you have had at least 3 hours of consecutive uninterrupted sleep.
4. Your temp can be taken orally, vaginally, or rectally. Make sure to use the same method throughout an entire cycle.
5. Plot your temp on your chart each day. Try not to read too much into any one temperature. It is best to look at your chart after, at least, one complete cycle. You are looking for patterns. It may take a few cycles to begin to see those patterns.
6. SOME women do have a temp drop when they ovulate. If you have a temp drop, it is best to have intercourse in case you are ovulating.
7. You are looking for a temp shift of at least .4 degrees over a 48 hour period of time. Please note that your temp will not always be the “normal” .4 degrees higher during the temp shift. It could be as low as .2 and still mean that you ovulated. The main thing is for your temp shift to be sustained for at least 3 days. Once this has happened, ovulation can be confirmed.
8. After your shift, or even at the end of your cycle, you can draw your cover line between the follicular phase and luteal phase temps. Then draw your line between the highest pre ovulation (follicular) phase and the lowest post ovulation (luteal) phase. The main purpose for this is to make sure your chart is biphasic.
9. As mentioned above, you are looking for patterns. If your temps have stayed up for at least 14 days past ovulation, you should be able to get an accurate read on a pregnancy test. If you get a negative test but your temps stay high for the next few days, try testing again. HCG levels vary so much from one woman to another. Perhaps your levels were just too low to pick up that first time.

*Please note that if you have irregular cycles, the biggest difference you will see should be in the follicular phase. Your luteal phase should remain pretty constant, not varying more than a day or so in any given cycle. Stress and other factors can cause you to ovulate late, but again, the luteal phase should remain pretty constant. Many women don’t know this and think that stress causes their period to be late. Not true. Stress can cause a delay in ovulation, making it “look” like your period is late, when in fact, you simply ovulated late. Once ovulation has occurred, your period will come anywhere from 12 to 16 days after, no matter what.

*You can also chart your cervical mucus and cervical position as well in conjunction with your BBT. The more you look at your fertility signs, the more you will know about your cycle and your body.

I charted on fertility friend and just loved it. Below is a picture of my chart using FF. This was when I was pregnant w/ #6.