Detecting ovulation with basal body temperature (BBT) charting is relatively easy and inexpensive. Your gynecologist or reproductive endocrinologist may recommend charting to help detect when ovulation is happening, or to get a better idea of your menstrual cycle patterns.
By charting your basal body temperature, you may discover that you've been missing the ideal time for sex (the three to five days before ovulation), or you might discover that you're not ovulating regularly. Over time, you may notice that you tend to ovulate on certain days in your cycle, helping you plan sexual intercourse that has the best chance of resulting in pregnancy.
Choosing a Basal Body Temperature ChartThe first step to charting your basal body temperature is getting a chart to record your temperature. You can find sample charts in some fertility books, such as Take Charge of Your Fertility (Harper Perennial, 1995) -- a book considered by many, including myself, to be the go-to resource for basal body temperature charting guidance.
Another option for charting is fertility awareness software, also known as fertility calendars. There are several fertility calendar options online, many of them free.
You could also make your own graph. If you make your own, you'll want to plot the temperature along the vertical, allowing one-tenth of a degree for each square. Along the horizontal, you'll have the days of your cycle.
Personally, I prefer using the computer because you can log a ton of information and reduce the chance of human error. Most ovulation software will automatically indicate when ovulation likely occurred, while plotting temperature yourself can leave you wondering if you're doing things correctly.
Once you have something to record your temperature on, it's time to start taking your basal body temperature.