Fertility health centre

Fertility charting: Your map to pregnancy

What is fertility charting?

It takes the average fertile couple five to six months to conceive. However, fertile couples who know when the woman is most likely to get pregnant and who make love frequently during that opportune time can often become pregnant much sooner.

How do you become one of these couples and increase your chances of getting pregnant earlier? By charting the woman’s basal body temperature (BBT). Learning about your fertility through a BBT chart is a very exciting way to get pregnant. It makes you understand your body and often gives trying to conceive (TTC) more of a purpose.

Recommended Related to Infertility & Reproduction

Exercise, weight and age - how do they affect your chances of conception?

Exercise should be encouraged as part of normal activities, for both women and men in the pre-conceptual period. However, strenuous exercise in women may result in disruption of the ovulation cycle, thereby affecting a woman’s periods. Normal exercise has not been linked to miscarriages (loss of pregnancy) but certain forms of exercise (for example, high-impact or contact sports or scuba diving) should be avoided in pregnancy. In men, over-exercise may cause a low sperm count.

Read the Exercise, weight and age - how do they affect your chances of conception? article > >

What is BBT in TTC?

Just what is your basal body temperature? Simply put, it's the temperature of your body at rest. For fertility charting it's always taken in the morning before you move or get out of bed. When the ovary releases an egg, it also releases the warmth-inducing hormone progesterone. That influx of progesterone typically makes body temperatures rise by well over two-tenths of a degree within one to two days after ovulation. This elevated BBT remains until the next menstrual period.

So there is a certain lower temperature pattern before ovulation (usually below 36.7°C/98°F), and an elevated temperature pattern after ovulation (usually above 36.7°C/98°F). This ovulation pattern is called a biphasic curve.

Biphasic means two phases. The first phase, the phase before ovulation, is known as the proliferative or follicular phase, the phase when the egg matures and develops. The second phase, the phase after ovulation or the postovulatory phase, consists of relatively elevated temperatures when compared with the first phase. That second phase is also known as the secretory or luteal or corpus luteum phase.

Your goal in charting is to find the typical biphasic pattern in the daily plotting of temperatures.

"Ah, I get it," you say. "'Bi' means two-two phases. Lower temps before the big 'O' and higher temps after." Exactly! The actual temperatures are not important; they are different from woman to woman. What is important is to check for the pattern of elevated temperatures that stay up for at least three or more days.

Why chart?

Fertility or basal body temperature charting is done for several reasons:

To see when and if you ovulate
To calculate the cycle length
To assess if you made love at the right time
To diagnose a pregnancy early on
To evaluate your cycle for fertility problems
To see if your fertility medication was successful
To correlate other fertility signs such as cervical mucus or cervical position with actual ovulation on a BBT chart (see Other Signs below)
To calculate the follicular and the corpus luteum phases (a key to possible infertility issues)