What is Basal Body Temperature (BBT) Charting and how can it assist with pregnancy? Read more below.

BBT is the temperature of the body on waking and rested – ie the temperature is at baseline.   In a typical menstrual cycle, a BBT will show body temperatures rising after ovulation and beginning to produce progesterone.

How does BBT help with fertility?

A BBT chart (recording a minimum of one full cycle) can confirm that you are actually ovulating and determine that your luteal phase (days after ovulation) is long enough to allow the embryo to implant.   Combined with observing your cervical mucus and other signs discussed in our consultations, this will be an excellent tool for your fertility practitioner to understand your peak fertility and address any irregularities.

Why is recording BBT over a full cycle important and what exactly are we looking for?

We want to see an increase in BBT after ovulation making your chart ‘biphasic’ – this means lower temperatures (36.2 – 36.4 degrees celsius or so) before ovulation in the follicular phase (pre ovulation), and higher ones (36.7 – 37 degrees celsius or so) after ovulation in the luteal phase.  Ideally, we will want to see your BBT charting over three cycles to observe these changes in your body and the impact of your acupuncture treatments.

What BBT can’t do?

BBT alone will not tell you when to have sex, as the change in temperature happens AFTER you ovulate (missing the fertile window for that cycle).  Instead it will help you to understand timings for future cycles, confirm you are ovulating and provide us, as practitioners, important information for your treatment approach.

How do I BBT?

  • Thermometer – you can use a standard thermometer, however, a BBT specifc one with two decimal places may be faster and more accurate 

  • First thing in the morning before doing anything.  Keep your thermometer on your bedside table.  A good tip is to leave it on your mbile phone so you remember.

  • Same time every day

  • It is best to take your BBT after a minimum of 3 hours uninterrupted sleep.

  • You can take the temperature orally or vaginally (but must be consistently the same).  Vaginally will be more accurate as if you are a mouth breather, orally may show lower temperatures.

  • Keep a record – you can do this manually or via an app.  The “Fertility Friend” free app is an easy one for us to read when you bring to your appointments.  Please be careful not to trust the dates that this app advises you are ovulated as the app tries to predict this based on your prior cycles, but will not necessarily read your body in that cycle.  Combining BBT with observing cervical mucus is our recommended method.  You may choose to also use ovulation strips around the predicted time of ovulation for further confirmation.

It is helpful to also note in your chart any irregularities (such as particular peaks in stress, poor sleep and stimulants such as alcohol the previous evening) as these may impact your temperature and can account for anomalies when reflecting back on the cycle.