Tempdrop is a revolutionary product that simplifies and enhances advanced fertility monitoring by tracking Basal Body Temperature (BBT). How is BBT connected to a woman's fertility and what's the proven science behind capturing it?
What Is Basal Body Temperature (BBT)?
Basal Body Temperature (BBT) is defined as the lowest natural, non-pathologic body temperature recorded during a period of rest. It is your base (basal) temperature at rest, usually reached during deep sleep when your body’s metabolism is the lowest so that minimal heat is produced.
BBT is influenced by the hormones in your body, varying with the different cycle phases. These slight temperature changes can be observed when measured daily to identify the pre and post-ovulation phases.
Traditionally, BBT results have been collected by measuring temperature upon waking. However, capturing a waking temperature, that is accurate enough to be used for fertility tracking, involves adhering to strict rules regarding sleep duration and avoiding movement before measuring.
Where on the body should we measure BBT?
Measuring core body temperature accurately is best achieved by placing a thermometer as close as possible to the body’s core, which is in maximal proximity to the heart.
The best way to measure core body temperature accurately is by placing an internal catheter into the pulmonary artery, which is one of the two major blood vessels originating from the heart (1). This catheter is called “Swan-Ganz catheter” and is inserted only in a hospital setting when intensive monitoring is required. This is an invasive and delicate procedure.
In day-to-day life, of course, this is not practical. However, studies have shown that continuously measuring skin temperature at the axilla is as effective as episodic axillary temperature measurement, even in hyper-sensitive populations such as cancer patients after chemotherapy treatments (2).
In another study completed with intensive care patients, a comparison was made among a range of alternative devices with core body temperature, using the Swan-Ganz catheter at the pulmonary artery as the reference. The aim was to identify the most valid and reliable technique for routine temperature measurements. The authors found that the gallium in a glass thermometer placed in the axilla for 12 minutes was the most accurate among all thermometers used in the study. The digital axillary measurement was equally as accurate and it was shown that using the gallium in-glass thermometer for 5 minutes resulted in a slight loss of accuracy compared to the 12-minute technique (3). Taken together, this data implies that the longer and more continuously you measure the axillary temperature, the more accurate an assessment of core temperature that can be obtained.
The Challenges With BBT Measurement
- The lowest BBT measurement is reached during deep sleep when the body’s metabolism is minimal. Manually taking a waking temperature doesn't truly capture our Basal Body Temperature (sleeping temperature). While it's a practical option for fertility tracking, the nuances involved can make obtaining consistent and accurate results more difficult. Therefore, tracking early waking temperatures may not provide truly accurate BBT readings.
- Skin temperature is affected by environmental factors. Therefore, care should be taken to measure the axillary temperature at the top of the axilla with the best possible thermal insulation.
How Tempdrop Has Addressed These Challenges
Tempdrop has developed a wearable sensor, worn over the axillary artery, enabling:
- Continuous monitoring of body temperature during sleep. This allows for the identification of a true BBT, rather than a single waking temperature measurement. Continuous measurements during sleep also facilitate the collection of other parameters that may affect BBT. For example, sleep duration, body movements, short periods of awakening during sleep, and more.
- To mitigate the effects of environmental temperature, Tempdrop integrated an additional sensor that accurately measures the surrounding environmental temperature without touching the skin. Complementing these features are proprietary algorithms that account for movement and environmental factors, to ensure optimal BBT measurement.
References:
- Fulbrook P (1993) Core temperature measurement in adults: a literature review. J Adv Nurs 18(9):1451–1460.
- Maarten van Vliet & J. Peter Donnelly & Carin M. J. Potting & Nicole M. A. Blijlevens. Continuous non-invasive monitoring of the skin temperature of HSCT recipients. Support Care Cancer (2010) 18:37–42
- Rubia-Rubia J. et.al. Measurement of body temperature in adult patients: Comparative study of accuracy, reliability and validity of different devices. Int J Nurs Stud 48 (2011) 872-80