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BBT and Fertility

Updated: Nov 30, 2023

The body basal temperature (BBT) chart records the body’s temperature on waking. All you need is a thermometer, a chart and a good night’s sleep! 🙁

I know some patients might be reluctant to do this, as they do not want to become obsessive, but it is a very useful tool for the practitioner for tracking and understanding the patient’s cycle. I would recommend you try, and you will be encouraged to see how your chart changes, as your body responds to treatment. 🌟

Always be sure to take the temperature before you get up, and at roughly the same time of day, as your temperature is said to rise 0.09’ with every hour.

There are a few things to watch out for:

1. The average temperature in the follicular phase is 36.2-5'. If it is below 36', this could be an indication of low thyroid activity - which can affect fertility -and might be associated with lethargy, weight gain and sensitivity to cold. From a Chinese medical perspective, it could indicate Yang deficiency of the Spleen and Kidney, Yang being the warming aspect of the body.

2. A follicular phase that is longer than 14 days may indicate sluggish production of oestrogen, or reduced sensitivity to stimulation by FSH, or perhaps inhibited FSH production by the pituitary, which results in slow development of the egg. In some cases, the egg might mature normally, but ovulation might be delayed by illness or stress and the egg will be overripe. From a Chinese perspective, it indicates that the Kidney Jing, (which relates to the reproductive hormones), or Kidney Yin (which provides the material foundation of the Kidneys, and which, compared to Kidney Yang, is cooling and moistening) are deficient or the Blood is deficient. All these substances are necessary to nourish the egg as it develoops.

3. If the follicular phase is short, the egg would not have had time to mature adequately, so the TCM practitioner has to work to nourish Qi and Blood and to clear Heat, to attempt to lengthen the phase. This may occur with hormonal imbalances, such as PCOS. It may also be that the pituitary gland is producing an excess of FSH, and the follicles are therefore recruited and matured too quickly. In some women, the follicles may be genetically programmed to make more FSH receptors than usual, so they will grow rapidly with less stimulation.

Don't worry if your follicular phase is short as a one-off. Sometimes a follicle may have started growing in the previous cycle, but not become the dominant follicle, but it escaped the usual atresia. In this case, it has had a head-start, so reaches ovulation in double-quick time.

4. If the follicular phase is too high, this is an indication of Heat, and possible hyperthyroidism, with weight loss and restlessness and rapid heartbeat. The endometrial lining may be too thin, and the cervical mucus may be too acidic and scanty and may contain antiserum antibodies. If the temperature doesn't drop immediately in the follicular phase, this indicates failure of Yang to transform into Yin, and may indicate incomplete expulsion of endometrial blood, such as happens when an endometrial implant outside the uterus, bleeds inside the pelvic cavity.

5. If the follicular phase is unstable, this indicates Heart and Liver Fire due to emotional stress.

6. As the follicle keeps growing, oestregen levels rise, the cervix should open and fertile mucus should be profuse. Once ovulation has occurred, the corpus luteum starts to produce progesterone, there is a surge in temperature, the cervix closes and the cervical mucus dries up. One of the functions of progesterone is to cause the endometrium to start secreting nutrients to prepare for conception, and it is vital for implantation.

7. The luteal phase should be 12-14 days long, and the rise in temperature should be 0.3-0.5. Variations of Kidney Yang Deficiency, the warming aspect of the Kidneys, which provides the motive force for transformation and development, would be indicated if there was a short luteal phase, a low luteal phase temperature, a slow rise in temperature, or an early decline. If the temperature is unstable, there could be Kidney Yang Deficiency, with concomitant instability of the Liver and Heart, which may be due to emotional stress, or a sudden surge in oestregen. This is something that should be addressed, so that it doesn't interfere with implantation at this crucial stage.

Tracking your temperature only gives you a heads-up about when you have ovulated after it has already happened, so it is not the best tool for predicting your most fertile window. It does, however, give you a vital window into understanding your menstrual cycle and identifying any imbalance. 🌟

BBT and Fertility monitoring

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