Which influences change the body temperature and how they affect the female cycle

In order for all the body’s metabolic processes to run smoothly, humans need a certain body temperature. However, this is never completely constant. It is subject to fluctuations that are influenced by many factors.

What is core body temperature?
Core body temperature (KKT) refers to the temperature inside a person and is normally between 36.5 and 37.4 degrees Celsius in healthy adults, but around 37°C on average. In babies and young children, the normal body temperature is slightly higher than in adults. It is around 37.5°C for newborns.

The core body temperature must be distinguished from the surface temperature, also known as the shell temperature. The surface temperature is measured on the skin and limbs. Compared to the core body temperature, it is subject to greater fluctuations and depends on external factors such as intense heat. In this case, the surface temperature may be higher than the core body temperature.

Fluctuations in core body temperature are quite normal
From person to person, this normal temperature can vary somewhat. The temperature value measured also depends on which orifice of the body is being measured, such as vaginal, oral, rectal, or axillary. The most accurate measurements can be taken vaginally and rectally. In addition, natural variations must be taken into account. They result, for example, from the time of day, from physical activity and, in women, from the different phases of the menstrual cycle. In women, the core body temperature rises by 0.3 – 0.5°C about 1 to 2 days after ovulation due to the thermogenic effect of progesterone.Day and Night Rhythm – The Circadian Rhythm
That your core body temperature fluctuates throughout the day (and night) is quite normal and nothing to worry about. At night, your core body temperature is lower than during the day. This is because you are not physically active during sleep, your body is resting and “conserving energy.” Due to various metabolic processes, core body temperature is lowest in the second half of the night and then rises slightly even before you wake up. It peaks in the afternoon – when it can be up to one degree Celsius higher than in the early morning – and then drops again. The day-night temperature curve resembles a sinusoidal curve and is also referred to as the ciarcadian temperature rhythm.

The lowest temperature point (nadir) is not reached before getting up, as assumed, but fluctuates individually by up to 3 hours according to research (Ekhart 2017). Scientists have thus proven that the nadir is not a stable point in the circadian temperature rhythm.

Even during a nap, your core body temperature drops somewhat. In the day view of your OvulaRing cycle curve, this is noticeable by a short, gentle drop in temperature and a gentle rise upon awakening.

Night sleep can be easily recognized in the day view of your OvulaRing cycle curve by the staircase-shaped drop in temperature. Of course, this depends on how fast you can fall asleep. If you fall asleep quickly, the drop may be steeper. If you have to get up during the night and are woken up by small children, for example, the OvulaRing day view of your cycle curve will again show a small rise in temperature, but not as high as during the day. When you fall asleep again, your temperature will drop again. All this can be tracked perfectly with OvulaRing.Fever
Febrile illnesses, as shown in our article image, are accompanied by an increase in core body temperature. At a core body temperature of 37.5-38.0°C, doctors refer to adults as having an elevated temperature (subfebrile temperature); at 38.1-39.4°C, they refer to a mild to moderate fever; and at 39.5-40.9°C, they refer to a very high fever. From > 41°C fever is life threatening, the upper limit of survival is 44°C. In your OvulaRing cycle curve, by the way, you can track exactly how high the fever actually is or was and to what extent any antipyretic drugs you may have taken are having an effect by measuring your core body temperature in high resolution. You can recognize a fever curve in your OvulaRing Cycle Curves daily view by the fact that your core body temperature often rises in a staircase and after recovery days later drops again in a staircase or with a jagged curve to normal temperature. When you look at your entire cycle with febrile illness, the temperature high quickly stands out as a kind of “jagged cone” as a “temperature outlier.”

Fever and fertility
A febrile illness can have a temporary negative impact on your fertility, resulting in briefly no ovulation or a shortened luteal phase until you recover. Fever puts a lot of stress on the body, so reproduction is temporarily “shut down” until recovery. With OvulaRing, you can track exactly how your body reacted to the fever, whether or not ovulation occurred, and when your cycle stabilized after recovery. Measurement accuracy and significance of OvulaRing are not affected by febrile illness.Sport
It is already known from sports science that humans have an increased body temperature during intensive sporting activity. During a marathon run, for example, the core body temperature can rise to around 39°C – the core body temperature thus increases by up to 2°C in the short term! Conversely, an increased body temperature is also a prerequisite for peak physical performance. Warming up beforehand improves various physiological processes and reduces the risk of injury.

Sport and Fertility
In your OvulaRing cycle curve, you can recognize the temperature peaks after your workout by a very steep, sharp temperature rise and rapid, steep temperature drop. This allows you to monitor exactly how much your body has heated up and cooled down. However, if you have a desire to have children, it is better to do moderate exercise, because too much intense exercise can reduce your fertility. It has been shown that ovulation is delayed or even absent due to too much exercise. We have also observed that high levels of exercise often result in a shortened second half of the cycle. Take these warning signals seriously and avoid excessive training – especially if you want to have children. With OvuaRing you can always see whether you are (still) ovulating and have a healthy second half of the cycle despite your workout or whether your fertility is negatively affected by too much exercise. The accuracy of OvulaRing’s measurement and its significance remain unchanged even during sporting activities.

Sauna
When you are in the sauna, your body temperature also rises rapidly to around 39 °C. The body can keep its temperature in the 60°C – 100°C hot air from rising further only for a short time by intensive sweating. For this reason, the recommended duration of a sauna session should not be exceeded. By the way, healthy saunas do not harm your fertility.Alcohol consumption
From the evaluation of OvulaRing cycle curves it became apparent that after an increased (one-time) alcohol consumption, such as after a party visit, a steep drop in temperature can occur during sleep. In this case, a short-term temperature drop of up to 35.5°C was observed.

Other influencing factors
Last but not least, other factors such as drug use, intense heat, but also extreme cold, physical exertion in everyday life such as climbing stairs, carrying heavy shopping, stress, anxiety and taking medication (e.g. progesterone) also influence your core body temperature.

With the high-resolution, continuous core body temperature measurement with OvulaRing, in addition to displaying your cycle curve and assessing your individual cycle health with fertile phase and ovulation time, even the smallest temperature fluctuations in the daily temperature curve can be displayed. By the way, in your integrated OvulaRing cycle diary you can document exactly whether you were sick, exercised, had to take medication and much more. This will help you later when interpreting temperature peaks.

Of course, our OvulaRing team of experts will not leave you alone during the cycle curve analysis and will be happy to advise you in detail about your cycle health and any questions you may have about individual temperature fluctuations during the course of the day.

References

Ekhart D et al. 2017. Dynamics of core body temperature cycles in longterm measurements under real life conditions in women. Chronobiology International. DOI: 10.1080/07420528.2017.1375942

Pschyrembel Fever – Pschyrembel online information: www.pschyrembel.de (as of May 2020).

OvulaRing cycle database