BBT Charting

Optimizing Fertility Part III: Analyzing your BBT chart in the luteal phase

In Part I and Part II in this series of articles on fertility and traditional Chinese medicine, we discussed the how’s and why’s of basal body temperature (BBT) charting, and how to analyze the follicular phase of your BBT chart. BBT charting is an incredibly useful tool in identifying potential fertility challenges, and optimizing your reproductive health in preparation for pregnancy.

This article focuses on BBT chart analysis of the luteal phase (post-ovulation phase), addressing some of the patterns that you are likely to see, and ways in which acupuncture and herbal medicine can be used to optimize fertility.

In review from the previous post, BBT should drop to its “base level” a day or two before the start of period. Base temperature, or starting temperature of the follicular phase, varies from woman to woman, and can also vary slightly from cycle to cycle. The average range for BBT throughout the follicular phase is 97.2° to 97.8°. Ovulation is the transition between the follicular phase and the luteal phase. Once ovulation has occurred, BBT readings should rise about ~0.5 to 1.0°F higher than temperatures during the follicular phase, and should be maintained at this level for about 12-14 days.

Temperature readings in this phase of the menstrual cycle tend to be more stable than readings in the follicular phase – ideally they do not vary more than ~.2°F. (See Figure 2.0) Temperature readings in the follicular phase are under the influence of the pituitary gland and the hypothalamus, both sensitive endocrine glands easily affected by factors such as stress and emotions, hence the tendency for fluctuations. Temperature readings in the luteal phase, however, are under the influence of the corpus luteum, a temporary endocrine gland that forms from the ovarian follicle that ovulated (released an egg). The corpus luteum produces progesterone, a thermogenic hormone, which is thought to account for the rise in basal body temperature during this phase. Acting as a kind of “adhesive,” it is responsible for maintaining the lining of the endometrium for the duration of the luteal phase…. and if conception occurs, then for some weeks beyond.


Basal body temperature typically drops about one to two days before the onset of the period – this temperature shift signifies that the corpus luteum is disintegrating and progesterone is no longer being produced. In response, the endometrial lining loosens and begins to shed – this is menstruation. In the event of conception and successful embryonic implantation, the corpus luteum will be maintained and continue to produce progesterone until the placenta takes over (around 8-12 weeks of pregnancy).

Your BBT chart can reveal the cause of menstrual cycle irregularities – if the follicular phase and/or the luteal phase are the issue. This is important to identify, as this information will more effectively guide your treatments. If the menstrual cycle is less than 28 days, this most often means that ovulation occurred early (i.e., short follicular phase), but occasionally, this may mean that the luteal phase is insufficient. Other potential insufficiencies include: your BBT in the luteal phase fluctuates too much, is slow to climb to an adequate temperature, never reaches an adequate temperature, or temperature drops too soon resulting in a short luteal phase. From a traditional Chinese medicine perspective, in all of these cases, the yang of the Kidneys is most likely deficient, and sometimes, in combination with other diagnostic patterns. Below is an explanation of the trends you may see in your BBT chart, and the ways in which acupuncture and herbal medicine may be of help in optimizing fertility.

The length of the luteal phase is a measure between ovulation and the first day of your period. The ideal length is 14 days, but 12 days is still considered adequate. If your luteal phase is short, about 8-10 days, there may be question as to whether there are sufficient Kidney energies (e.g. progesterone production) to support embryo implantation; it is helpful to support the Kidney yang at this time (See Figure 2.1). If the luteal phase is around 5-7 days, both Kidney yin and yang tend to be weak. If the luteal phase is less than 3 or 4 days, it is possible that ovulation is not actually occurring; in these cases, deficiency of Kidney energies is more severe (See Figure 2.2). In both cases, acupuncture and herbal supplementation throughout the cycle is advised. It will be especially important to support healthy egg maturation in the follicular phase – this builds the necessary foundation for the progression of a healthy cycle. To explain, it may be said that the yin (follicular phase) is the basis of yang (luteal phase) – so if the yin is weak, yang cannot adequately grow. Acupuncture and herbal supplementation to support Kidney yin and yang are typically prescribed; if deficiencies are especially severe, the jing (basis of all Kidney energies) will also need to be nourished.

For some women, luteal phase temperature can run too low. The average range for BBT throughout the follicular phase is 97.2° to 97.8° – there is not truly an average range of temperatures in the luteal phase, but rather, what is significant is the ratio between BBT readings in the two phases. Post-ovulation, BBT readings ideally rise and are maintained at about ~1°F higher than average temperature in the follicular phase (See Figure 2.3). Again, this sustained rise in temperature is due to progesterone production, and ideally, does not vary by more than .2°F throughout the luteal phase. A low luteal phase is due to a weakness of Kidney yin, leading to a weakness in Kidney yang. In some cases, qi and blood will also need to be supplemented to support the yang – all of this may be done through the application of acupuncture and herbal medicine.

Ideally, luteal phase temperatures remain stable; if temperatures fluctuate by more than .2°-.3° they are considered unstable. If temperatures rise adequately at ovulation time, but then drop and rise dramatically over the course of the luteal phase, the diagnosis is usually Heart and Liver qi stagnation, coupled with Kidney yang deficiency (See Figure 2.4). Similar to temperature instabilities in the follicular phase, stress is often a key factor. If temperatures peaks are especially high, Heart and/or Liver fire has developed. To treat this pattern, blood tonics to soothe the Heart and Liver are prescribed, as well as herbs to support Kidney yang. Managing (and minimizing) stress will be helpful, and necessary, over the long term.

If temperature rises adequately at ovulation time, but then drops dramatically about one week after ovulation (and rises again to a stable temperature), this is typically due to a surge of estrogen in the luteal phase (See Figure 2.5). Similar to the previous pattern where there are dramatic fluctuations throughout the luteal phase, the diagnosis is usually Heart and Liver instability, coupled with Kidney yang deficiency. The difference here is that the Kidney yang is not so much deficient, but rather “less firm.” Because this is a sensitive time in the cycle for a woman who is trying to conceive – potential implantation time – treatment to soothe the Heart and Liver and boost Kidney yang are prescribed; reducing stress is also of utmost importance.

Ideally, the initial BBT surge that signifies ovulation is a significant one – around ~0.5 – 1.0°F – and happens over the course of one to two days. If your luteal phase temperature rises too slowly, taking three or more days, your body may be slow to respond to the circulation of progesterone making the actual day of ovulation more challenging to pinpoint (See Figure 2.6). Traditional Chinese medicine classifies this pattern as Kidney yang deficiency combined with Spleen qi/yang deficiency; Liver qi stagnation may also be a factor as it has a tendency to impede timely ovulation. Treatment to support the Spleen and/or Liver early mid-cycle, and Kidney yang in the luteal phase is recommended; reinforcing Kidney yin at the beginning of the cycle may also be helpful.

It is normal for temperatures to drop about 12-14 days into the luteal phase (the day or two before the period) – this indicates decreasing progesterone levels and the onset of menses –  but if BBT drops rapidly and continuously after ovulation, Kidney yang and Spleen qi tend to be deficient (See Figure 2.7). In this case, the length of the luteal phase is adequate, but declining temperatures reveal another weakness. If a higher BBT is not being sustained (e.g., low progesterone levels), this indicates that Kidney yang is in decline; there may also be spotting, indicating that Spleen qi is unfirm. Treatment will involve supporting the Kidney and Spleen during the luteal phase.

If your luteal phase temperature does not drop, this usually indicates pregnancy (See Figure 2.8). About ten days after ovulation, it is possible for a sensitive pregnancy test to detect sufficient levels of human chorionic gonadotrophin (hCG) for a positive result. Your BBT chart may also reflect a second slight spike in temperature due to embryo implantation in the days after ovulation; slight spotting may also be seen as a result of the embryo burrowing into the endometrium.

It must be noted that while it is uncommon for the luteal phase to last longer than 14 days, it can occasionally last up to 16 days. If your temperature remains elevated 16 or more days post-ovulation, and then drops, this may be indicative of an early stage miscarriage. Another potential reason that BBT may not drop at this time is the presence of a corpus luteum cyst: pregnancy tests will be negative, but BBT will be sustained and the period delayed due to continued progesterone production. Corpus luteum cysts are uncommon, and typically resolve on their own.

I hope you have found this series of articles on basal body temperature and chart analysis helpful. If you are interested in learning more about how to optimize your fertility, you may be interested in my FREE online course on BBT charting. Learn more HERE.

Be Well,

Dr. Jules Bogdanski, DAOM L.Ac.