How to take and when to take!
Many women take their temperature when trying to conceive to confirm if they are ovulating or not, by taking your temperature from the begining of your cycle to the end you should be able to see the first part of your cycle showing low temperatures for around 12 to 14 days followed by a rise which confirms ovulation and then for yout temperatures to stay elevated for a further 10-16 days.
You will need a Basal body thermometer to take your temperature with, Basal body thermometers are able to pick up slight changes in temperature than just a standard thermometer.
I sell Basal Body Thermometers in my fertility shop on this site.
Its best if you take your temperature around the same time every day, you can take it via the mouth or vaginally but what ever way you choose you need to continue to take it that way throughout the month.
Place the thermometer in a place where you can easily reach it as you need to take it as soon as you open your eyes, do not sit up or move anything other than your arm as this can effect your temperature, i always found it was easier for me to slip mine in my pillowcase of my pillow along with a pencil and a piece of paper (in a pillowcase is better than under the pillow as it can't slip down the back of the bed and a pencil is better as it can't run out or all of a sudden stop working)
Make sure you have had atleast three hours of uninteruppted sleep before taking and do not drink or eat anything before taking your temperature.
In the first part of you cycle you will see lower temperatures this is down to the hormone estrogen once ovulation has occurred your temperatures rises this is down to progesterone released from the follicle after ovulation.
To draw your coverline you need to look for the previous 6 temperatures before the rise/ temperature shift which showed you have ovulated, find the highest temperature and draw your line 1/10 of a degree higher than the highest temperature in the 6 day block.
By taking your temperature and noting down other fertility signs such as cervical mucus,ovulation pain and noting down results of opks you will be able to see if you are ovulating, get a idea of when you ovulate if you have been charting for three months and how long your luteal phase is.
Sample of a BBT chart, this chart is a pregnancy chart, notice how the temperature stays elevated., 2nd chart shows how cm mucus changes.
Click on the images for a better view.