You've probably heard plenty about the temperature graph, but what exactly is it? The basal body temperature chart, or temperature graph, shows you where you are in your menstrual cycle, so you know when your most fertile period is. How does it work?

- Fisrt of all, you need to ask your doctor or chemist for a chart on which to plot your graph. You can also download one from www.babycentre.co.uk or www.fertilityplus.org.

- Take your temperature at the same time every morning, preferably as soon as you get up, using the same thermometre. Be as precise as you can.

- You should see your temperature rising every day, then a sudden decrease. This will be followed by a steady low temperature for a few days, before it goes back up again, which is when you ovulate. This is usually during a 24-hour window, but the changes are very slight and it is best to ask your doctor to take a look at your chart, rather than try to interpret it yourself.

- So when is your fertile period? The day you ovulate is obviously the most fertile day of your cycle, but you will also be very fertile in the two or three days leading up to it.
Basically, your temperature graph is a good guide to your cycle, if you are finding it hard to conceive, but you don't need to run out and buy a thermometre as soon as you start trying! Keep calm and keep it all in perspective.