The basal temperature gives you an important clue to your fertile days. Do you want to get pregnant? Then you can know by the so-called temperature method when your ovulation takes place. We explain how to measure the basal body temperature correctly and how it helps you get pregnant.
Basal body temperature is the body temperature you have in the morning after waking up. It is usually the lowest measurable value of the day. As you sleep, your body shuts down the temperature and uses the energy for regeneration processes. Shortly after ovulation, however, this value increases by at least 0.2 degrees Celsius – in some women, temperature fluctuations of up to 0.5 degrees Celsius are possible. By taking regular temperature measurements and recording these results in a temperature curve, you can determine the time of your ovulation.
Measuring the basal temperature: That’s how it works
Measuring temperature, in addition to observing the cervical mucus that changes over the course of your cycle, belongs to the possibilities of natural family planning. Of course, you can get pregnant without measuring the basal body temperature. But the method helps women with a desire to have children understand how their own body is ticking and when the fertile days are. Incidentally, the temperature method is therefore also suitable as a natural method of contraception – more on that later.
What you need for a meaningful basal temperature curve, above all, is a lot of discipline in measuring. That means:
- Measure the temperature daily in the morning, just after waking up and while you are lying – before getting up.
- Miss always at the same time, so measuring errors can be reduced.
- Take the measurement either orally (in the mouth), vaginally (in the vagina) or rectally (in the buttocks). Keep the location of the measurement for at least one full cycle.
- Use a thermometer on which decimal digits can be read.
- If you are using a mercury thermometer, be careful to knock it down in the evening. This short movement can already increase your basal body temperature if you need to measure shortly after that.
In the pharmacy you get very accurate thermometers, so-called basal thermometers, usually together with cycle sheets, in which you can enter the values and the time of the measurement. Another way to build your temperature curve is, for example, the turbine cycle calendar. Many women also rely on unique ovulation apps, with which one has the basal temperature curve always – even on the go – in view.
Temperature measurement: What else you have to pay attention to
Several factors can distort your temperature. Among other things, you should have slept for at least six hours before you measure the temperature. Alcohol consumption or a cold can falsify the temperature. The same applies if you regularly take medication because certain drugs provide different readings. In this case, ask your gynecologist if your medication affects your body temperature.
Other factors can affect the validity of your basal temperature curve:
- You did not ovulate.
- You have been subjected to significant mental and physical exertion.
- You work in shifts or have an irregular day-night rhythm for other reasons.
- There were deviations at the time of measurement.
Where should I measure?
If you want to measure the basal body temperature, you can choose freely whether oral, vaginal, or anal. Basal thermometers are usually suitable for all three areas. The important thing is that you stay with them once chosen method.
I measure orally, and I’m pretty sure most women choose it. It is the most comfortable.
Six tips for better measurement results
1. Close your mouth!
When measuring the temperature thermometer under the tongue and mouth too! Do not open your mouth. That could affect the temperature. You have to measure at least three minutes. If you want to be sure, you should expand to five minutes – even if the digital thermometer has been beeping.
2. Five hours of sleep is the minimum!
If you want to measure the basal body temperature and want to prevent it effectively, you have to be (unfortunately) a bit disciplined. The reason: You must have slept for at least five hours to get a reliable temperature.
It is enough if you were half asleep in the toilet one hour before the actual getting up. That already messes up the system. I had to travel a lot for a while and changed the time zones more often. In these months there was nothing to measure the basal body temperature.
A friend of mine had big problems with the basal body temperature. She always noticed big jumps in the curve. It then told me that she makes a party now and then. That’s precisely what messed up the curve. If you take medication, often have heartache and worry, or suffer from stress and insomnia, you should choose a different method. All these factors affect your basal body temperature.
3. Check the charge level of your cycle computer or thermometer
Over time, I’ve had some surprises now and then. Once my cycle computer stopped working. I forgot to charge the battery …
The day had gone. If you have to get up first and look for batteries or power outlets, you can forget the day. Measuring basal temperature only works if you stay in bed after waking up.
4. Shakedown the analog thermometer beforehand
If you use an analog thermometer, you have to shake it down immediately after the measurement. If you shake it in the morning before measuring, you sit in bed and the temperature of the body changes.
5. Do not measure in the ear or under the armpit
In the ear or under the armpit you should never measure! Use this method to see if you have a fever but do not create a precise basal temperature curve.
6. Do not replace the thermometer during a cycle
Incidentally, the thermometer must never be replaced during a cycle. But the nuances in the temperature rise are too low, and each device is calibrated differently.
The desire to have a baby: that’s how the results help you
If you are at a fertility wish to know your fertile and infertile days with measuring your body temperature and the resulting temperature curve, you need to note that the values can be over after three cycles indicate whether and when did you usually your ovulation.
It is essential: If your temperature rises slightly in the middle of the cycle and stays high until the next menstrual period, you have ovulated. Keep an eye on this increase in basal body temperature, which will tell you when to increase your chances of getting pregnant.
It is good to know that a mature egg can be fertilized for 12 to 24 hours, after which it dies. But as sperm survive several days in the fallopian tubes, you should already have sex on the days before ovulation, even before the temperature rises. Depending on the length of the cycle, this time begins approximately from the 10th day of a new menstrual cycle.
If the elevated temperature remains high even over the days of expected menstruation, this is considered a sure sign of pregnancy. To be on the safe side, you should do a pregnancy test or visit your gynecologist.
If you do not get pregnant
A desire to have a baby that does not immediately come true can take your mind and become so strong that the disappointment increases with each passing month. If you know for certain that you can have children and your partner is capable of birth, then you should have patience first of all.
Did you know that only about a quarter of couples who wish to have a child fulfill this wish in the first three months? The majority wait about nine months to a year for the good news. So there is enough time to take a closer look at one’s own body and to recognize the physical signs of ovulation and fertile days.
Prevention: How does the symptothermal method work?
If pregnancy is (just) out of the question for you, you can naturally use the temperature method to prevent it. A big advantage of natural contraceptive methods is that the method does not artificially interfere with your hormonal balance. Also, you will get to know your cycle well. And you will find that once you have measured your basal body temperature for a few cycles, you slowly develop a sense of the values in your temperature curve. Then you can read off your barren days on your basal temperature curve. So you know in which period you have to abstain or have to resort to contraception.
Nevertheless, since several factors and ovulation can influence the method cannot be accurately predicted, you should use a complementary natural method for safety reasons. The so-called Pearl Index indicates how reliable a contraceptive method is. The higher he is, the more uncertain the contraceptive method. The Pearl index in the temperature method is 2.0 – compared to the pill, for example, between 0.1 and 0.9. (A Pearl Index of 2.0 means: Of the 100 women who use this method for one year, two become pregnant.)
One possibility is the combination of a so-called symptothermal method, in which you combine the temperature method with the cervical mucus observation, also called the billings method. For that, you not only record your warm-up temperature every day but also the consistency of your cervical mucus. The observation of the cervix can also be combined with the other methods.
A disadvantage of the temperature method is that you have to have a regular everyday routine and a monthly cycle so that the values are not distorted. Keep in mind that the method (as opposed to condoms) is not suitable for the prevention of sexually transmitted diseases.