Temperature & Cycle Charting
Your Basal Body Temperature (BBT) fluctuates with the hormonal changes in your body. Charting these changes gives you a glimpse into what's happening behind the scenes and can help you determine both hormonal imbalances and your "fertile window" - the time that you are most likely to conceive and the best time to have intercourse on order to conceive.
The basic driving factor behind temperature monitoring is the raise of temperature after ovulation due to the increased level of progesterone. You cannot really predict ovulation ahead of time with the use of the data of only a single cycle, but you can determine when it has happened, after the fact. When combining your observations over a long period of time you will be able to predict ovulation more accurately by using an average across many cycles.
To make effective use of your observations, you need to log your temperature at the same time every day, first thing in the morning when you wake up, before you do anything else. Once you get going your temperature will rise due to your metabolic rate increasing. Use a chart like the following: Example Chart to note down your temperature. Use a digital thermometer with at least one decimal display.
The temperature chart below indicates the ebb and flow of temperature across an average 28 day cycle. Notice the drop (day 13) and sudden rise (day 14). That drop in temperature is what you need to monitor.
The hormonal chart below shows the rise and fall of the most important hormones in your menstrual cycle. You can read more about these here. Note especially the increased level of progesterone in the second half (lutheal phase), this is what causes your temperature rise. Progesterone is necessary to build and sustain a healthy endometrial lining (uterine lining) to support and sustain a pregnancy until the placenta is sufficiently developed to nurture the baby.
The ideal time to engage in intercourse in order to conceive will be the 24hr timeframe right before the spike in temperature. Sperm can survive up to 48hrs, and sometimes up to 5 days in fertile cervical mucus.
For an exhaustive guide and online facilities for temperature charting you can download the Fertility Friend Handbook for Cycle & Temperature Charting, or visit www.fertilityfriend.com