A BBT Charting guide for pinpointing ovulation
- Claire Norton MBaCC
- Apr 3
- 4 min read
Updated: Apr 6
BBT (Basal Body Temperature) charting is one of the most useful and underrated tools for tracking ovulation and understanding what’s happening in your cycle. It can help confirm whether ovulation likely happened, and flag potential issues like short luteal phases, low progesterone, or thyroid imbalances—all without a blood test.
If you’re trying to conceive or just want to get a clearer picture of your hormones, here’s how to get the most out of BBT tracking.
What Is BBT and Why Does It Matter?
BBT is your resting temperature, taken first thing in the morning before you move, drink, or even sit up. It follows a biphasic pattern:
Before ovulation, temperatures are lower, typically between 36.1–36.5°C.
After ovulation, temperatures rise by 0.5–1°C due to progesterone.
If pregnancy doesn’t occur, BBT drops before your period starts.
This shift from lower temps to sustained higher temps is a clear sign that ovulation likely happened, which is essential if you’re trying to conceive or assess hormonal health.
BBT cannot predict ovulation, but it can show that it has already happened, making it a valuable diagnostic tool.
How to Track BBT Accurately
For reliable readings, consistency is key. Here’s what you need to do:
Take your temperature at the same time every morning, before getting out of bed.
Use the same thermometer and location (oral or vaginal) throughout your cycle.
Ideally, you need at least 5 hours of uninterrupted sleep (harder if you have young children, but do your best!).
For oral readings: Place the thermometer in your mouth and wait 10 minutes before turning it on and taking the reading—this helps stabilise the temperature.
Track external factors like illness, alcohol, travel, stress, or poor sleep, as these can affect BBT.
The earlier you wake up, the lower your temperature may be; the later, the higher.
If you start seeing unusual readings, change the battery in your thermometer.
Most digital thermometers from Amazon will do the job, or you can use a wearable device like Tempdrop, Oura Ring, or some Apple Watches for overnight tracking.
What Can BBT Tell You About Your Cycle?
1. Ovulation Timing
BBT helps pinpoint when ovulation has likely occurred by showing a clear temperature shift- but it doesn’t predict ovulation.
An advanced tip - When tracking your BBT, if you record three consecutive temperatures that are higher than the previous six days, that sustained rise is a strong indicator that ovulation has occurred.
2. Luteal Phase Health
The luteal phase (from ovulation to your period) should last 12–14 days with consistently higher temps. A luteal phase shorter than 11 days could indicate low progesterone or luteal phase defect, which may benefit from progesterone support, acupuncture, or nutrition.
3. Thyroid Function
Consistently low BBT (pre-ovulatory temps below 36°C) may suggest low metabolic rate and thyroid dysfunction may be suspected, especially if accompanied by symptoms like fertility issues, fatigue or hair loss. In this case, thyroid testing (TSH, Free T3, Free T4) would be a good next step.
4. Period Prediction
BBT drops at the end of the luteal phase, so tracking it can help you anticipate when your period is due.
5. Early Pregnancy Detection
If your BBT stays elevated for 18+ days after ovulation, it could be an early sign of pregnancy. If you haven’t took a pregnancy test by this date it would be recommended. However, most have often tested already by this point.
6. Delayed drop in BBT
Women who suffer with endometriosis may notice a delay in temperature drop at the beginning of the cycle.
In one study of infertile women, 67% of those with untreated endometriosis showed a slow decline in basal body temperature during the first few days of their cycle—compared to just 7% of women without the condition, suggesting a clear association between early follicular temperature patterns and endometriosis
BBT from a Chinese Medicine Perspective
In Chinese medicine, BBT can also give insights into syndromes and diagnostic patterns.
Consistently low BBT or a weak temperature rise after ovulation could indicate Kidney Yang Deficiency, a Spleen Qi Deficiency or a combination.
An unstable second half of the cycle (BBT fluctuating rather than staying high) may indicate Heart and Liver Qi instability combined with Kidney Yang Deficiency.
In TCM, the Chong Mai (Penetrating Vessel) is closely linked to blood flow, the uterus, and menstrual health. In cases of endometriosis, there is often blood stasis and stagnation, meaning the Chong vessel may not empty smoothly at the onset of menstruation. This can result in a delayed or gradual BBT drop rather than the typical sharp decline seen in an uncomplicated cycle.
Higher-than-expected follicular phase temperatures can indicate internal heat, which might be due to Liver Qi stagnation transforming into heat or Yin deficiency, all of which can impact fertility. An acupuncturist would focus on clearing heat during this phase, depending on the root cause.
Fertility acupuncture and Chinese herbs can help regulate temperature shifts, balance hormones, and optimise cycle health for conception
Combining BBT Tracking with Cervical Mucus & Position
BBT is even more helpful when combined with cervical mucus tracking.
Before ovulation: Rising oestrogen makes mucus clear, stretchy, and slippery (like raw egg whites).
After ovulation: Progesterone thickens mucus, making it creamy or dry.
Checking cervical position can also help. Before ovulation, the cervix is:
SHOW: Soft, High, Open, Wet.
After ovulation, it lowers, firms up, and closes.
Tip: Checking in the shower after washing will ensure your hands are clean.
BBT Charting: is it worth it?
BBT charting takes a bit of commitment, but it’s one of the best ways to understand your cycle without invasive tests. It can help you:
Confirm ovulation
Spot cycle imbalances early
Understand how stress, illness, or nutrition affect your hormones
Feel more in control of your fertility journey
Even if you’re working with a fertility specialist, BBT charts provide invaluable insights that can help guide your treatment. If it’s something that may cause additional stress, you may find it easier to focus tracking your cycle and fertile mucous only.
BBT tracking just provides an extra layer of information which is invaluable when working with a fertility acupuncturist.
If you’re struggling to interpret your BBT charts or suspect imbalances, I offer personalised fertility acupuncture in Leicester. I also use Kindara so clients can share their charts with me for tailored advice.
So informative and interesting ❤️