When I first learned about Basal Body Temperature (BBT), I thought it was just a way to pinpoint ovulation. And while that is one of its main uses, I have more recently discovered that BBT tracking can reveal so much more—about hormone health, menstrual cycle patterns, and even how the body responds to stress or illness.
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What is BBT?
BBT refers to your body’s lowest resting temperature within a 24-hour period. It’s best taken first thing in the morning—before getting out of bed—after at least 3–4 hours of uninterrupted sleep.
To get started, you’ll need a basal thermometer (digital or wearable, like Ovusense) that reads to two decimal places. As you chart your temperature daily using an app or a paper chart, you’ll begin to notice patterns that reflect what’s happening hormonally throughout your cycle.
Why Does It Matter?
BBT is directly influenced by hormonal changes throughout the menstrual cycle—especially progesterone, which rises after ovulation and causes a small but measurable increase in body temperature (typically 0.2–0.5°C). A sustained rise in temperature confirms that ovulation has occurred. This is key, as many apps can only predict ovulation based on averages—they can’t confirm whether it actually happened.
Beyond identifying ovulation, consistent BBT tracking can reveal a great deal about overall hormonal health. A well-charted BBT pattern can indicate:
- Whether ovulation is occurring (an essential factor for conception)
- Luteal phase length and stability (critical for implantation and progesterone support)
- Potential thyroid dysfunction (suggested by consistently low temperatures)
- Signs of adrenal stress or fatigue (reflected in erratic or unstable patterns)
- Physiological responses to illness, poor sleep, or travel
When used correctly, BBT charting becomes a valuable tool for assessing menstrual health, supporting fertility, and gaining deeper insight into the body’s hormonal rhythms.
Who Should Track BBT?
BBT is for anyone who wants to:
- Understand their cycle more deeply
- Track ovulation (whether trying to conceive or using natural contraception)
- Identify potential hormonal imbalances
- Support their fertility in a more empowered, informed way
- See how stress, sleep, or lifestyle shifts are impacting their body
And no—you don’t need to be trying for a baby to benefit. I really wish this kind of cycle awareness was taught in schools as part of basic body literacy!
BBT tracking can also help highlight patterns that may point toward underlying hormonal imbalances—such as those seen in conditions like polycistic ovary syndrome (PCOS), endometriosis, perimenopause, or menopause. While BBT can’t diagnose these conditions, it can provide helpful insights that you can explore further with your healthcare provider or holistic practitioner.
What Your Chart Can Reveal
Your BBT chart shows how well the follicular phase (before ovulation) and luteal phase (after ovulation) are functioning.
If there’s no clear temperature rise, it may be a sign that your body isn’t ovulating—your ovaries may not be consistently releasing an egg.
After ovulation, we want to see a steady temperature increase, driven by progesterone, that holds until just before your period begins. If your temperature rise is inconsistent, drops early, or doesn’t sustain, it could signal low progesterone. That can contribute to PMS symptoms, but more critically, it may affect implantation and the maintenance of a pregnancy.
This is why I now recommend BBT tracking to so many of my clients. It’s an accessible, empowering tool—and when used alongside reflexology and other holistic supports, it can make a meaningful difference in how you understand and care for your reproductive health.
As always, if you have any questions, please feel free to reach out—I’m happy to help. You can contact me directly or connect with me over on Instagram.
Gráinne
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GráBeo Holistics by Gráinne Staunton 
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