Here’s how to use the basal body temperature (BBT) method to find your ovulation
To give yourself the greatest chance of getting pregnant, you need to know when you are ovulating each month. Luckily, through the changes of your basal body temperature and cervical mucus you can predict when it will happen.
Mapping your body temperature and cervical mucus can give you a clear picture of your cycle. You can do this using our blank chart.
Remember that every woman’s cycle is different, and that yours is the same from month to month.
When you are ready to begin charting your body temperature and cervical mucus, do the following:
- Print a copy of our blank chart and buy a good two-decimal digital thermometer.
- From the first day you get your period (first day of your cycle), take your temperature before getting up in the morning and mark this on the chart with a dot. Connect the dots every day to see how your basic temperature fluctuates from day to day.
- At the same time, when checking your temperature, check the consistency of your cervical mucus. Record this using the abbreviations on the chart, e.g. P = period, D = dry, S = sticky, E = egg-white-like. Mark the days you have your period with a P.
- At the end of your cycle, go back and look for the day you ovulated. It is usually the last day that your cervical mucus corresponds to egg-white or the following day. It is also usually associated with a decrease in temperature, followed by a slight increase lasting three days. Circle the day of your cycle when you were ovulating.
- Continue charting your cycle for the next few months and start a new blank chart on the day you start your period.
- You can also use ovulation test and write the result into the chart, as an extra help to predict when your ovulation will happen. Get a guide to ovulation testing here
- Look for patterns in your cycle. You may notice if you ovulate on the same cycle day, or you may notice other patterns that appear. For example, you probably have two or three days of ovary-like cervical mucus before you ovulate, while a permanent rise in temperature signals the end of your fertile period. Of course, every woman’s body is different, so it’s up to you to read the signs.
- Make sure to have sex every other day during your most fertile period for the best chance of getting pregnant.
Read in-depth questions and answers on the temperature method below.
What is the basal temperature method?
When you want to get pregnant and find your most fertile days, you can use several different methods to help. The basal temperature method also called BBT (Basal Body Temperature) is one of them. The method can also be used preventively – though with much less certainty compared to most other contraceptives.
The basal temperature method was first mentioned in 1953 by an English professor Marshall, and the method is based on the thermal effects of progesterone in the brain’s thermal conduction center.
The basal temperature method is a good method for charting your cycle if you have been trying to get pregnant for a long time without success. Also women who for various reasons cannot or will not use traditional fertility products such as ovulation test, may choose to use the basal temperature method.
Keeping track of changes in your basic body temperature over time will help you see when you are most fertile, and therefore when it is best to have sex.
What is the method about?
The basic temperature method is to measure the temperature daily to determine when ovulation has occurred.
The body temperature is usually below 37ºC in the first part of the menstrual cycle, but is increased by approx. 0.2 – 0.4ºC about one to two days after ovulation in most women (individual variations may occur). The temperature then remains at the elevated level in the remainder of the cycle and the lower temperature only remains after the menstruation has begun.
What is required to use the method?
In order for the method to work you will need a two-decimal-quality digital thermometer with a minimum accuracy of 0.1 ° C.
The temperature should be measured when you wake up in the morning before getting up and before eating or drinking anything (even before going to the bathroom). The measurement should be done at about the same time each day and the same thermometer should be used every time.
Babyplan digital thermometer can be a good choice here, as it has several advantages compared to many other thermometers on the market, including it’s illuminated display, which is very handy on dark mornings (you are free to turn on the light and wake your partner and / or children). The thermometer also has a soft and flexible tip which makes it less difficult to hold in the mouth during oral testing.
In addition, Babyplan digital thermometer can store up to 30 temperature measurements.
In order for the basal temperature method to work, one must accurately record the measurements – perhaps over a long period of time. For this purpose, you can download and print our blank BBT chart where the temperature is recorded day by day so that a clear picture of the menstrual cycle can be seen with time.
Are there any downsides to using the basal temperature method?
It should be noted that it is not always easy to use the basal temperature method – as there may be several other reasons for a somewhat elevated body temperature, e.g. a small infection, alcohol, hot or cold drinks, stress, anxiety, flight / jet lag or heavily spiced food.
To get the best possible information from your measurements, it may be a good idea to list all the factors that can affect the temperature chart, so add your own codes / symbols for it as to keep track if possible.
It is also necessary to be accurate with the measurements and to keep going – it may take time before you have learned how to interpret your temperature curves.
Cycles without ovulation occur naturally in most women once in a while. In such a cycle, one will not see a rise in temperature.
The basal temperature method provides information on when ovulation has already occurred. The egg lives for a maximum of 24 hours after it is released from the fallopian tube, and if it is not fertilized during its life, no conception can occur during that cycle.
How do you interpret your measurements?
The evaluation of the temperature diagram is generally called the “three over six rule”. This means that after registering 3 consecutive days of elevated temperature compared to the average of the last 6 days before the increase, you can assume that you have ovulated.
Can all women use the method?
Women who have shift or night work should not use the method. This is because the body reaches its basic body temperature only after 4 hours of continuous sleep. In the event of no sleep or continuous awakenings, it will increase the basic body temperature.