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What is a Triphasic Chart and How Does It Relate to Fertility?

There are so many different tools and resources to guide you on your fertility journey — some might say too many! Parents-to-be can quickly become overwhelmed with all the information, particularly if they’re just starting to grow their family.

One of these tools is a triphasic chart. As the name suggests, a triphasic chart measures three different temperature rises, and this pattern is thought to be a potential sign of fertility.

However, it’s important to remember that the only way to confirm your pregnancy status is to take a pregnancy test. Triphasic charts can be useful, but they’re not always accurate and should only be used in coordination with other tools and resources.

Continue reading to learn about triphasic charts and how they relate to fertility.

What DPO does triphasic shift?
What DPO does triphasic shift?

What Is a Triphasic BBT Chart?

A triphasic basal body temperature (BBT) chart is commonly used in fertility tracking to describe a specific pattern observed in a woman’s temperature readings during her menstrual cycle.

Basal body temperature refers to the body’s lowest resting temperature, typically measured upon waking up in the morning. In a triphasic BBT chart, there are three distinct temperature phases.

Initially, temperatures are relatively low during the follicular phase, which is the first half of the cycle. Then, after ovulation, a noticeable temperature rise marks the beginning of the luteal phase. However, in a triphasic chart, an additional temperature increase occurs around 7-10 days after ovulation, creating a third, higher temperature phase. This potential third shift in temperature is often associated with the implantation of a fertilised egg, and some women interpret it as a positive sign of pregnancy. This pattern can be observed in the above chart.

However, it’s important to note that while a triphasic pattern can be encouraging, it does not guarantee pregnancy, as individual cycles can vary.

Reliability of Triphasic Charts

Regarding the reliability of triphasic charts in predicting pregnancy, it’s important to exercise caution and manage expectations — as is the case with every fertility tool and resource at your disposal.

While some women view a triphasic pattern as an encouraging sign of pregnancy, you should understand that it is not a definitive indicator. The only definitive indicator is a pregnancy test performed by a healthcare professional, generally the second step following a home pregnancy test.

Triphasic charts have been observed in both pregnant and non-pregnant cycles, which means that the pattern alone cannot confirm pregnancy with certainty.

Other factors like stress, illness, disrupted sleep patterns, or hormonal fluctuations can also contribute to temperature variations, potentially leading to a triphasic pattern even in non-pregnant cycles.

What Causes Triphasic Temperature Shifts?

Triphasic temperature shifts can occur for many reasons other than pregnancy. While the exact cause may vary from woman to woman, there are a few main factors that can contribute to a triphasic pattern on a basal body temperature (BBT) chart:

Sleep disturbances or irregularities

Sleep patterns or sleep quality disruptions can affect basal body temperature readings. Inadequate sleep, an irregular sleep schedule, or ongoing restless nights can influence body temperature and potentially contribute to a triphasic pattern.

An increase in hormone activity

Fluctuations in hormone levels, such as oestrogen and progesterone, can impact basal body temperature readings. Factors like stress, illness, certain medications, or hormonal imbalances can cause hormonal fluctuations, resulting in temperature variations and a triphasic chart.

Inflammatory response

During an illness, the body’s immune system releases various chemicals and triggers an inflammatory response to combat the infection. This immune response can increase body temperature, resulting in a higher BBT reading during the illness phase.

It’s important to remember that while these factors can cause a triphasic chart, they do not necessarily indicate pregnancy. It is always advisable to consult with a healthcare professional for an accurate interpretation of BBT charts and to discuss any concerns or questions regarding fertility or pregnancy.

When Is the Best Time to Take a Pregnancy Test?

If you’re keeping track of your basal body temperature and notice a triphasic pattern, is that an indication that you should take a pregnancy test?

Taking a pregnancy test certainly won’t hurt, but it’s not the only symptom you should look for. Early pregnancy symptoms can include a missed period, breast changes, fatigue, nausea or morning sickness, increased urination, food cravings or aversions, mood swings, and a heightened sense of smell. However, it’s important to note that every woman’s experience is unique, and some may have few or no symptoms.

The best time to take a pregnancy test can depend on the type of test you are taking. For example, Fertility2Family’s range of pregnancy tests enables you to reliably test for pregnancy up to seven days before your expected period is due. Other brands may not be as sensitive, and using them this early may produce inaccurate results.

Generally, the best time to take a pregnancy test is typically after you’ve missed your period. This is when the pregnancy hormone hCG levels (human chorionic gonadotropin) are usually detectable in urine. However, for more accurate results, it’s recommended to wait until at least a week after your missed period or follow the instructions provided with the specific pregnancy test you’re using. It’s always best to consult a healthcare professional with concerns or uncertainty.

Does triphasic chart mean pregnancy?
Does a triphasic chart mean pregnancy?

Fertility2Family is the best place to shop for affordable fertility products. Plus, our blog is jam-packed with expert advice on pregnancy — including basal body temperature monitoring — to help maximise your chances of conceiving. Contact us today if you have any questions about our product range.


Fertility2Family only uses trusted & peer-reviewed sources to ensure our articles’ information is accurate and reliable.

Dr. Sheena Vaughan (Registered Chinese medicine practitioner) (2021) Basal body temperature chart: BBT chart for ovulation, Qi Medicine Acupuncture Melbourne Fertility and Pregnancy. Available at: (Accessed: 16 October 2023).

Rachel Gurevich, R. (2020) Can a triphasic BBT chart be an early sign of pregnancy?, Verywell Family. Available at: (Accessed: 16 October 2023).

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Evan Kurzyp

Evan is the founder of Fertility2Family and is passionate about fertility education & providing affordable products to help people in their fertility journey. Evan is a qualified Registered Nurse and has expertise in guiding & managing patients through their fertility journeys.

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