Charting your ovulation cycle is a great way to determine how long you are actually ovulating. This method is most useful with women who have a regular 30-day menstrual cycle. The Basal Body Temperature test measures the change in temperature that occurs after ovulation, making it easier to predict when ovulation will begin on your next cycle.
Day one of your chart is the first day of your menstrual cycle. You should take your body temperature as soon as your period begins, record it, and then keep the thermometer on your bedside table. The same thermometer should be used each time to ensure accuracy. Then, each morning before you get out of bed, take your temperature again and record the information. Your basal body temperature will rise by about .4°F – .6°F just after ovulation. So the day ovulation occurs you will see a rise, and over the next two days your temperature should climb even higher, making it easy to see when you are peaking.
The tricky part about charting your temperature is noticing that your post-ovulation temperature will remain at the new, higher level. When the temperature drops, your cycle starts over again. Don’t get discouraged; the important thing to note is that the rise on the day of ovulation doesn’t stand out from the normal ups and downs in the pre-ovulating phase. It’s usually only recognized in retrospect when it forms an upward line with the rise in your temperature over the following two days. If you stick with it, taking your basal body temperature can be a helpful tool in the months to come, as you become better at predicting when you will ovulate.