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. We recommend that you chart your basal body temperature fluctuations using the free online tool at OvaGraph.

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.

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I started wed morning taking temps
Wed 97.2
Thurs 96.2
Fri 96.8
Sat 97.0
Sun 97.8 with a positive ovulation test on Sat and Sunday. Can anyone help me with this ovulation schedule. I have had the stingy mucus throughout all the days? Help!!! I thought that the spike in temp tell you that you already ovulated but the ovulation test positive are suppose to mean I will ovulate in the next 72 hrs. I have PCOS And take. 1000mg metformin daily.

My husband really wants a boy...all boys. I was reading up on natural ways to aid in conceiving a boy and I found that the Ph level of your mucus during ovulation does have a role in the gender of your baby. If the Ph level is highly acidic then the female sperm will thrive. However, male sperm do best in a high alkaline environment. If you are trying for a girl, eat a "high acid" type food (tomatoes are good) about one hour before your lovemaking. Want a boy? Try eating an avocado or other type of high alkaline food about an hour before. I searched, "natural ways to conceive a boy" on google and found lots of information. hope this helps someone.

I just started BBT charting to make sure that I was ovulating. My temps during my cycle are at about 96.3-96.4 and then the day after my cycle jumped up to 97.4. Is this normal?? does that mean I ovulated a day after my cycle?? Have not finished a whole month of charting, but just thought that this was really strange. Last month I don't think I ovulated or missed my day as I was using OPK for LH serge. Have had 2 MC and when I did get preggo I ovulated 8-9 days before my next cycle was supposed to start. This may be a LP problem. Seeing a specialist next week about it.


I've just started taking my bbt in hopes to understand a pattern before we start TTC. But seriously it's been like a rollercoaster. These numbers come from days 19-29 of my cycle.

96.3, 96.5, 97.2, 96.6, 97, 96.7, 97.2, 96.7, 96.8, 98.2

I've been off Birth control for nearly 2 months now. My last cycle (first one off BC) was 34 days long but other than that normal. Anyone else experience these roller coaster variations in temp?

I have read that male sperm swim
Faster and also die faster. They only last 24hrs
Female sperm are slower but live longer, about 72 hrs.
What all this mean is that I your looking for a boy you need to have sex within 24hrs from ovulation. Otherwise may be a girl.
I have had 2 friends who have tries this theory and it has help them conceive the gender they were Hoping.
Google 'conceiving a boy', and lost of info will come up on this.

Good luck!

I am also starting TTC. I was diagnosed with pcos and was prescribed clomid. Didn't work. I was not ovulating, my body was resistant to clomid. Also, my period was unpredictable, my cycles could be 35 or 45 days long. I would seldom have a 60 days cycle.
The following year my husband got me to do a cleansing(detox) and I started to treat my fertility naturally. I was taking a bunch of supplements like primrose oil, master G and FCS II along with seeds (sunflower, sesame, flaxseed, pumpkin) that improves reproductive function, 2 for 2 weeks and the other 2 for the following 2 weeks. I also learned how to manage my stress, which is an important variable in my cycle.
After 4 months, i noticed my period getting regular. My cycle came down to 31 days. After 2 mo ths came down to 30 days amd after stoping te aupplements and seed it came down to 28 days.
Today I'm TTC and am charting my bbt. According to what I have seen on the intenet, my bbt is normal and now I am able to see/presict when I'm Ovulating. I'm very optimistic.
I hope this helps all of you.

I've been married for 7 years and my husband has a kid for his past gf I am jealous of what they have he visit his children once a month and his screen picture in his phone is his 3 kids and in his wallet picture. It really hurts me because we dont have even 1. my doctor told me my fallopian is open my problem is just my egg cell is too small and she said I need to take femara and the last one she injected me to explode and release my egg.I tried HSG, CLOMID,FEMARA, VITAMIN E, FOLIC ENHANSID 5mg, HUMAN MENOPAUSAL GONADOTROPHIN and i for got the last injection my doctor gave me. i ALSO FOLLOWED ALL HER INSTRUCTION. she also gave me a date when to try for baby making.and today is my schedule for my check up and so happy it is possitive. try to search all my medicine I take it may help you.too

My husband and I really want a little boy.... It seems like it will not happen. He has 2 daughters from a previous relationship and I have 1 daughter from a previous relationship and 2 daugthers with my husband. which is 5 daughters..... HELP PLEASE the gender selection procedures are so exspensive!!!!!! Anybody do the baking soda douche to raise the ph?

My husband and i have been trying for 7 yrs to get pg its to a point already were seeing babies n pregnant woman dont bother me i gave up on trying if it happens it happens oh well!!

Take your opk test around 2pm because it usually takes about 4 hours from the time you wake up for lh to be detected. It is very possible to miss your lh surge and never get a positive opk even if you test every 24 hours

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By TTC veteran and mother of two, Elizabeth Andrews.