Measurement of temperature during the cycle

Why measure the temperature?

Measuring temperature during the menstrual cycle can be helpful in determining fertile days and recognizing potential health problems, such as abnormal hormone levels or thyroid disorders, which can affect the menstrual cycle and body temperature.

How does temperature change during the cycle?

Body temperature usually changes during the menstrual cycle. When ovulation occurs, the temperature may increase by a few tenths of a degree (usually between 0.5 and 1) Celsius. The elevated temperature then persists in the second phase of the cycle. If fertilization does not occur, the temperature drops again before  menstruation, if a woman becomes  pregnant temperature remains  slightly elevated.

Why does this happen?

Temperature fluctuations during the menstrual cycle are caused by hormonal changes that occur in a woman’s body. During ovulation, when an egg is released from the ovaries, the level of progesterone in the blood increases. This hormone causes the body temperature to slightly increase. If there is no pregnancy at the end of the cycle, the progesterone level decreases and the temperature drops . During menstruation, the temperature should return to typical values (around 36.6°C).

Progesterone helps regulate body temperature by impacting the thermoregulatory system. Progesterone stimulates the nervous system to produce heat by increasing the production of cAMP (cyclic adenosine monophosphate). This in turn leads to an increase in body temperature. So when the level of progesterone in the blood increases, the body temperature may also slightly increase.

Why do we need an increase in progesterone during the cycle? What is its function?

During ovulation, progesterone production increases because the hormone is necessary to prepare the uterine lining for fertilization and implantation of the fertilized egg. Progesterone also decreases contraction of uterine muscles and maintains an appropriate thickness of the lining, which facilitates implantation of the embryo and maintenance of  pregnancy. If fertilization does not occur, the level of progesterone decreases, leading  to the death of the uterine lining and the start of menstruation.

What  is the best way to measure temperature and under what conditions?

The consistency of the measurement conditions is very important, because we need to compare the results without additional variables. Therefore, it is important to measure temperature under the same conditions every day, that is at the same time, in the same position of the body and in the same place. The best time to measure temperature is in the morning, after waking up, just before getting out of bed. To achieve the most accurate results, it is necessary to avoid physical exertion, stress, and taking thermogenic medications (those that increase heat production) before taking the measurement.

Where to measure the temperature, what to pay attention to?

You can measure the temperature in the oral cavity, in the vagina, under the armpit or in the rectum. In any case, the measurement should take about 3-4 minutes. In the case of electronic thermometers, we usually receive a sound signal when the measurement is complete. Importantly, choose one place and stick with it, because changing it can falsify the results.

The most stable and constant temperature is in the rectum, as it provides the most accurate result. However, not everyone may feel comfortable with this measurement method.

If you measure temperature in the oral cavity, you should also choose one place, such as, under the tongue or between the cheek and teeth, so that the temperature reading is reproducible.

If you want to measure the temperature in the vagina, lie on your back and gently insert the thermometer into the vagina so that it touches the wall but is not pressed in too deeply. Make sure you do not have an infection because the body temperature may be elevated in this case.

It is important to remember that the temperature in the vagina can be slightly higher than the body temperature measured in other places. Therefore, you need to be especially careful not to change the measurement conditions.

When measuring temperature under the armpit, make sure that the thermometer is placed as deeply as possible and does not touch the clothing.

Is it necessary to measure temperature every day?

In order to obtain  the most reliable results, it is necessary to measure the temperature every day, otherwise, we will not be able to notice differences in its height. After a few weeks of daily observation, you will probably notice a certain pattern of temperature fluctuations , but this is  not always the case . Women with irregular cycles will get results that are not entirely in line with a pattern, and in a given cycle ovulation may not occur. All of this will affect the final result, but the more data you have, the more you can  learn about your own body.

What can affect the results of temperature measurement?

Many factors can affect the results of temperature measurement, which is why it is important to minimize the variables. It is believed that in the morning, after several hours of sleep, without changing position, without physical exertion or stress, the results should correspond to BBT (Basal Body Temperature).

Temperature fluctuations  can be influenced by:

  • illnesses and infections
  • change of time zone or shift work
  • heavy physical exertion
  • stress
  • intense nocturnal activity
  • alcohol consumption before measurement
  • medications

What is the best way to measure temperature during the cycle? What is an ovulation thermometer?

Of course, we measure the temperature with a thermometer. The simplest thermometer for a few euros is enough , but you can also consider one that gives the result to two decimal places (then the results will be more accurate, such a device is an ovulation thermometer). What is important is to conscientiously record the results of the measurements, for example, in the iYoni application.

How to add temperature measurement to iYoni?

To do this:

  • go to the iYoni application, make sure you are logged in
  • on the main screen, click on “Enter your temperature today”
  • enter the measurement result
  • decide if you want the application to remind you about future measurements (it’s worth it!)
  • click on “Add measurement”

If you make a mistake, you can easily change the result, you can also add the result to the previous or any other day. If you want to see how your temperature has changed over time, go to the reports feature.