Ovulation CalendarClocking Edge Software

“I am thoroughly impressed with the Hormonal Forecaster’s ability to interpret my charts. I’ve entered data from eight past cycles and found it to perform wonderfully on all of them.”

-- Jen (Florida, USA)


The key to controlling your fertility is to understand when ovulation occurs. Whether you desire to achieve pregnancy, natural family planning techniques can help accurately identify your ovulation.

Natural Family Planning

Natural Family Planning (NFP) is a technique that utilizes natural indicators of fertility to identify ovulation. This approach is highly effective as it utilizes the Symptothermal (Sympto-Thermal) method. Personal information is recorded on a daily basis and charted. Natural indicators of ovulation such as basal body temperature, cervical mucus characteristics, and/or cervix position are used to gauge fertility. This information is typically combined into an ovulation chart to facilitate interpreting your fertility. Charts can be constructed manually from your personal records or automatically using charting tools and ovulation calendars like the Hormonal Forecaster.

Basal Body Temperatures

Basal body temperature is one of the most common indicators of ovulation used. It is particularly useful in identifying ovulation after it has occurred.

Once temperatures have been recorded, the values can be graphed on an ovulation chart. When ovulation occurs, a woman will experience a sustained temperature shift. It is this temperature shift that is used to pinpoint ovulation. A biphasic chart can be characterized by this upward temperature shift and accurately identify the cycle day upon which ovulation occurs.

Basal body temperature readings need to be taken carefully to ensure accuracy. It is recommended to take readings immediately after waking in the morning. This maintains consistency in the day to day temperatures by avoiding other influential variables encountered later in the day. Potential inaccuracies in the readings should be noted on your ovulation chart for later interpretation. These can be caused by later than usual waking, illness, prior alcohol consumption, or stress.

Cervical Mucus

Cervical mucus is another indicator of fertility. It is a particularly useful indicator for women trying to get pregnant since it reveals ovulation as it approaches. Information about the consistency and sensation of cervical mucus is recorded on a daily basis.

Highly fertile mucus is thin and stretchy and can be characterized by a wet or slippery sensation.

Cervical mucus records are typically included on your ovulation chart with your basal body temperatures. This makes it possible to use both indicators to determine ovulation and assess your fertility.

Cervix Position

Women can also track the orientation of the cervix as part of natural family planning. Right before ovulation, the cervix will transition from a low to a high position. After ovulation it will return to its low state. Its position can also be helpful in tracking fertility, although it is frequently omitted in favor of tracking the other symptoms.


The symptothermal approach to natural family planning combines these indicators to identify ovulation. This is usually done in the form of an ovulation chart which summarizes your symptoms over one menstrual cycle. Temperature data is graphically plotted while cervical mucus and cervix position are indicated below. By looking at the ovulation chart, one can accurately gauge their fertility through interpretation of each of the symptoms tracked by natural family planning. Reading your chart takes practice, but it is a skill that can be easily acquired.

Ovulation Predictors

For women who are trying to get pregnant, other indicators of fertility such as ovulation test results should also be incorporated into their charts. These tests detect a surge in a woman’s luteinizing hormone (LH) which coincides with the release of an ovum into the fallopian tube. Fertility is typically highest in the three days following a positive ovulation test. A woman’s optimum fertility usually falls within the following 12-48 hours. The idea behind charting is to include as many indicators of fertility as possible to assist in determining when ovulation occurs. For this reason, it is also important to include ovulation test results on your chart.

The Calendar Method

The calendar method (rhythm method) is a less sophisticated estimate of fertility. It estimates ovulation on the premise that all women ovulate 14 days prior to the start of their next menstrual period. This is not always the case for everyone though. For this reason, the symptothermal approach to fertility tracking advocated by natural family planning is preferred. Still, the calendar method has its merits. Most noticeably, it does not require as much daily recording. For some women, this advantage is worth the decreased effectiveness.

The Hormonal Forecaster includes all of the tools necessary to help you calculate ovulation so that you can gauge your fertility. This includes all techniques discussed on this page. It can even try to help overcome the main shortcoming of the calendar method if temporarily used in conjunction with natural family planning techniques. When other indicators of fertility such as basal body temperatures and cervical mucus observations are used to estimate ovulation across many cycles, a more appropriate luteal phase length can be selected. This custom value can be used in place of the default 14 days although its precision will still depend upon the regularity of your cycle. While it cannot produce results as precise as the symptothermal approach to natural family planning, the calendar method can be appropriate for those with flexible fertility needs.

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