Have you ever wondered how to read your basal body temperature chart (BBT)? I almost always ask my acupuncture patients to complete a BBT chart when they come to my clinic because it is such a useful tool to understand many different aspects of hormonal balance and fertility. I am often asked by patients seeking fertility treatment, “Can you really tell all of that just by looking at the BBT chart?” and the answer is definitely –yes! You may know already that ovulation can be mapped from BBT charting, but did you know that learning to read your BBT chart can give you incredible information about different hormonal imbalances in your cycle and in your body as well? This article will go through the basics of reading BBT charts. To download a basal body temperature chart on which you can record your information please click below.
How to record your basal body temperature chart
Take your temperature on waking after at least 3 hours of sleep. Take your temperature immediately on waking, without getting up or moving about too much. Try to take your temperature at the same time each day as well, or your reading may not be accurate. If the time varies please make note of this, as well as any illness (cold, stomach ache) or interrupted sleep as this may affect the temperature readings you get.
If you look below, you will see an example of a BBT chart for what we would consider a typical cycle.
Phases of your chart
The first phase which you see is known as the Follicular Phase. This is the phase in which the follicles develop. Typically we like to see that this level is low and steady. Estrogen is the dominant hormone during this phase.
Around midcycle, you may or may not see a slight dip in temperature. Following this, you will see a strong rise in temperature of approximately 1 degree. The day before the temperature rises is the day you ovulate.
The second phase is known as the Luteal Phase. This is the phase in which the egg travels down the fallopian tube and the process of fertilization or implantation may occur. Typically we like to see that this phase is high and steady. Progesterone is the hormone which keeps the luteal phase at a high temperature. We also like to see that this phase is consistently around 14 days in length.
What do my readings mean?
Phase 1 - Follicular Phase - Low Temperature
When the follicular phase lasts too long, is too short, too high or low, or is unstable this can mean that there are hormonal imbalances which vary from thyroid conditions, to emotional stress. For example, emotional stresses often show up as an up and down movement of temperature from day to day.
The follicular phase tends to shorten as the ovarian reserve decreases, as follicles tend to go through premature recruitment and development in this case. If you have noticed that your preovulatory phase has been shortening consistently, check your ovarian reserve markers. Any of these changes can be normal in one given cycle, but if you notice that there are consistent changes, have your hormonal markers checked.
Conditions which affect Phase 1 readings
In thyroid disorders, we will tend to see an abnormally low or high temperature reading in this phase. In the case of stress, we tend to see instability of temperature, and in the case of primary hormonal imbalance we tend to see either an increase or decrease in length of this phase. In polycystic ovarian syndrome this phase can be longer than usual, indicating insulin resistance or excess androgens(male hormones). Insufficient nutritional elements and decreases in blood circulation to the uterus can also cause this phase to be abnormally long.
Phase 2 - Luteal Phase - Higher Temperatures
Midcycle, we see a spike in temperature, which is related to secretion of the hormone progesterone and is the result of ovulation. The temperature will rise the day after ovulation occurs. If you don’t see this spike, you may not have ovulated.
If the temperature reading in the second phase of the cycle (luteal phase) does not remain steady, your progesterone secretion may not be enough to maintain implantation and pregnancy. If the length of this phase is either too long or too short, this can indicate problems with the health of corpus luteum, or nutritional deficiencies (the corpus luteum is the outer part of the follicle left after you have ovulated, which continues to secrete the hormone progesterone allowing you to maintain pregnancy).
Temperature changes in Phase 2
If there is a downward decline occurring earlier than 12 days after ovulating, this suggests that there may not be sufficient progesterone production to maintain pregnancy. Implantation may occur 7 – 12 days after ovulation, in which case you may see an implantation dip on your chart. This is a normal and healthy finding, but like implantation bleeding it is also not necessary for a healthy pregnancy. There are many other more complex breakdowns of the variations in basal body temperature charting as well.
I find that looking at the basal body temperature chart of my patients allows me to pinpoint specific imbalances for each woman. Most unexplained infertility cases are actually not infertile at all, but are actually subfertile. Through looking at charts as well as lab results and symptoms, the cause can often be found. Charting can be an excellent tool for diagnostics especially in cases of unexplained infertility.
References for this article
- Lyttleton, Jane.(2004) Treatment of Infertility with Chinese Medicine. Churchill Livingstone