Measure basal body temperature and determine ovulation

Back to blog

Determine your ovulation with the basal body temperature

The progression of the basal body temperature during your menstrual cycle provides information about your fertility. The progression of the basal body temperature during your menstrual cycle provides information about your fertility. This is because around ovulation, the body's core temperature rises (and with it the lowest value of the body's core temperature, the "basal body temperature"). Because women are only fertile around ovulation, this rise is an important fertility indicator. On this page you can learn more about what basal body temperature is and how it can help you determine your ovulation.

What is basal body temperature?

Shortly after ovulation, your body temperature regularly increases by around 0.2 degrees compared to the first half of the cycle. The fact that this works so reliably is due to the hormone progesterone, which is increasingly released after ovulation. Among many other effects, it increases your body temperature in the second half of the cycle. When the temperature rise has occured, you know: you have ovulated!

However, it is not enough to just measure the temperature once, because the temperature level alone does not tell us how high the progesterone is. So what we need is a temperature history to see that your core body temperature (or the lowest value, the basal body temperature) has risen relative to the other temperature values. The basal body temperature is the lowest core body temperature your body reaches when at rest – that is when you are sleeping. It is usually measured in the second half of the night, i.e. in the very early hours of the morning.

  • Basal body temperature and ovulation

    Ovulation is the moment when the mature egg makes its way to the uterus, and can already be fertilized. You can tell that you've ovulated by looking at your core body temperature. After ovulation, a hormone is released: progesterone. This causes the core body temperature to rise, by about 0.2°C. However, it is not enough to measure the temperature just once, because the temperature level alone does not tell us how high the progesterone is. Therefore, to determine an increase, a temperature profile is needed. With trackle you can easily measure your body's core temperature and monitor temperature development. trackle evaluates according to the rules of the symptothermal method: This means that in addition to the core body temperature, the consistency of the cervical mucus is also evaluated. This double verification makes the method so secure!

  • Basal body temperature and pregnancy

    Observing your basal body temperature not only helps you to determine whether you have ovulated, but also whether you may be pregnant – this is particularly interesting for all women who want to have children. After ovulation, the temperature rises and stays at this higher level until the next menstrual period. Then a new cycle begins and your core body temperature drops again. However, if you do not start menstruating and your basal body temperature remains at a higher level for at least 18 days, it may be time for a pregnancy test or a visit to your gynecologist.

What is the best way to measure basal body temperature?

It is best to measure the basal body temperature inside the body, because: While your body temperature inside the body always remains relatively constant so that your organs can work properly, the temperature on the skin surface is subject to greater fluctuations. The further away from the body core the spot where the temperature is measured, the greater the fluctuations. If you tend to have cold feet or hands in winter, you will be familiar with this effect: The extremities react much faster to cold with lower blood flow than the inside of the body. For the same reason, it is also recommended when taking a temperature that this is best done in the ear, mouth or buttocks. Even under the armpit, the body temperature can sometimes be subject to considerable fluctuations. It is therefore not easy to take meaningful basal body temperature readings, unless you measure inside the body, as the monitor does.

Measure basal body temperature: reliable with trackle

What external factors can influence the values?

  • External factors cause the basal body temperature to rise without ovulation having already taken place. Very important: each of us is different and also reacts differently to stress and so on. You can recognize a "disturbed" temperature value by the fact that your temperature rises suddenly for a day or two and then drops again.

  • Common confounding factors that affect basal body temperature in many women include:

    – Drug consumption

    – Unusual consumption of alcohol

    – Short/disrupted night’s sleep

    – Stress

    – Time change

    – Cold or illness

In trackle you have the possibility to exclude a disturbed temperature, which is not taken into account for the evaluation. But because we all react so differently to disruptive factors, your temperature doesn't necessarily have to rise, even if you're stressed or have a cold. Therefore, it is important that you do not immediately be alarmed just because you have gone to a party or have a cold: only when these can affect the measured temperature.

For whom is basal body temperature monitoring suitable?

trackle and the symptothermal method They work for everyone: breastfeeding women, women with shift jobs, women with irregular menstrual cycles, women who want to have children, women who want to get to know themselves and their bodies better, and women of all ages.