Home > Predicting Ovulation > Basal Body Temperature: BBT Charting

Basal Body Temperature: BBT Charting

Fertility Charting allows you chart and predict ovulation based on calendar patterns, cervical mucus analysis, and changes in your body temperature - or Basal Body Temperature charting.

Basal Body Temperature (BBT) and Ovulation Prediction

One of the many changes that take place in a woman's body during her menstrual cycle is an increase in body temperature at the onset of ovulation. During the first the first part of a woman's cycle, the body temperature is lower. With ovulation, the body temperature rises (to create a more fertile environment for the fertilized egg) and remains higher until the beginning of a woman's next cycle. The temperature increase is driven by the hormone progesterone, which increases when you ovulate.

Recording each day's body temperature - and charting the pattern of temperature changes - will help pinpoint when when ovulation has occurred and determine future patterns for predicting ovulation. Note that a sudden rise in your basal thermometer reading does not mean you are about to ovulate - it means that you have just ovulated. By charting, you can determine meaningful patterns that allow you to predict fertility in future cycles.

Because BBT charting allows a woman to confirm the onset of ovulation, it is a very useful method in helping facilitate conception - as well as understanding the general patterns and nuances of a woman's menstrual cycle.

During the first two weeks of a woman's cycle, her body temperature is lower (97.0 to 97.5 F), due to the presence of estrogen. With ovulation, a rise in body temperature takes place - caused by an increase of the hormone progesterone - in order to provide a warmer, more fertile environment. A minimum temperature rise of 0.4 to 0.6 degrees F can be measured - and this change will last through the duration of the menstrual cycle. By monitoring when this temperature change takes place, you can estimate when ovulation has taken place. You can find a digital basal thermometer designed for BBT charting here.

How to take your Basal Body Temperature    

Your Basal Body Temperature can be taken orally with a special BBT thermometer. Ideally, a larger thermometer that registers from 96 to 100 degrees (in easy-to-read one-tenth degree increments) is recommended. Digital thermometers are also available. Remember, you are attempting to discern as little as a two-tenths of a degree of difference in temperature, so selecting a quality thermometer and following directions are crucial.

Important: Your BBT temperature refers to a 'resting' or 'base' temperature. That means that your BBT must be measured prior to any physical activity, after at least three to four hours of sleep. Make sure that you read thermometer directions - and if you have any questions or unique considerations, consult your physician.

1. Taking Your BBT Temperature

Take your BBT temperature first thing each morning - as soon as you wake up. You must remain in bed (as physical activity can increase your temperature) and avoid eating or drinking or even moving. Either insert the thermometer in your mouth - or alternatively your rectum - and wait five minutes. Read the temperature to within 1/10 of a degree and record the reading.

2. Charting Your BBT Temperature

Starting on day one of your menstrual cycle - the first day of your period - begin recording your BBT temperature using a calendar or notebook and graph paper. Each morning, record your temperature. Plot each day's BBT on the graph. Your temperature rise may be sudden, gradual, or in steps. The pattern may vary from cycle to cycle.

3. Predicting Ovulation

For most women, 96 to 98 degrees is considered normal prior to ovulation and 97 to 99 degrees after ovulation. By charting the differences - in one-tenth degree increments - you can determine when ovulation has taken place. Typically a rise of at least 0.4 to 0.6 degrees will take place at ovulation, though for different women the temperature increases may be sudden or gradual. Over time, charting your BBT will help you predict ovulation.

BBT Limitations in Ovulation Prediction

BBT charting only tells you when ovulation has already occurred - and is therefore important for predicting general patterns. To predict ovulation, LH testing (ovulation predictor kits) is more effective - and examining cervical mucus is also a very valuable method.

> Return to Fertility Charting
> Observing Cervical Position
> Ovulation Testing

Comments

i found a new monitor that measures temperature for me while I sleep.
It's a patch and i get a simple answer.
I had been charting for 7 months and the early mornings were driving me insane. however I now appreciate my sleep a lot more!

they have an offer at the moment pregnant in 12 months or your money back... let's hope!
www.duofertility.com

AnaB - Aug 20, 2009
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I've been tracking my temperature and during the week of predicted ovulation, my temperature didn't change. Does this mean I did not ovulate? Also I've taken 3 months worth of ovulation predictor tests and have always tested negative. We've been trying for a year to conceive with no luck.

Anonymous - Aug 04, 2009
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Hi, as long as you have had 3 hours of sleep, you can take your body temp. Its up to you, but you must take your body temperature at roughly the same time everyday....so you choose either 2.30 or 6.30.
2.30 is probably the best bet......as your sleep may be disturbed later.

I am charting at the moment and thats what I have been told to do.

Hope this helps.

Anonymous - Jul 23, 2009
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My husband works a night shift which requires him to get up at 2:30 am. I always get up and get his lunch fixed then go back to bed and get up at 6:30 am to get myself ready for work. When should I take the temperature, at 2:30 am or 6:30 am? I want to do this the right way because we've been trying for two years and miscarried in Feb 2009. Anyone with information, please let me know. Thanks and good luck to all of you.

Anonymous - Jul 20, 2009
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This method really helped us to conceive quickly. It allowed me to get in tune with my body, understand my cycle, & then get our timing just right.

Anonymous - Jun 30, 2009
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First Day of Last Period:
Cycle Length:
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Luteal Phase Length:
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Ovulation:
Due Date:
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Note that you are most likely to get pregnant if you time your lovemaking to occur on the days right before - and on - your ovulation date. Keep in mind that the projected ovulation date above is simply a “best guess” estimate based on your cycle date information. The most accurate way to pinpoint your most fertile time is through the use of urine-based ovulation tests or with a fertility monitor. We have partnered with Early-Pregnancy-Tests.com, the Internet’s leading supplier of preconception products since 2001, to offer low-cost, FDA-approved pregnancy and ovulation tests – with free same-day shipping.

 

Now that you’ve calculated your ovulation date using our ovulation calculator, we have a number of other helpful tools you can use to help increase your chances of conceiving.

 

  • Create your own personalized ovulation calendar! You can even provide an email address so that you receive email alerts of your most fertile days, when you can begin testing for pregnancy, and more.
     

  • Create your own personalized fertility chart! This is a highly accurate way to pinpoint your ovulation date that relies primarily on basal temperature charting. (Visit Early-Pregnancy-Tests.com for an accurate, inexpensive basal thermometer.)
     

  • Connect with others at our online community! If you have questions about trying-to-conceive – or if you just want to vent a bit – we have a wonderful, vibrant community of people who’d just love to hear from you.

Find your most fertile time.
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