How to take your basal body temperature for fertility charting

Even though we’ve all taken our temperatures from time to time, it’s often something that can be intimidating for those just starting to practice the sympto-thermal method. Personally, I was afraid of having to wake up at the exact same time daily or going to bed at totally different times would throw everything off. There are a couple of reasons you don’t have to worry:

1. Cervical fluid is more important, anyway.
2. Your temperature probably isn’t as freakishly sensitive as you think. If it is, you will figure that out just by taking your temperature daily and know what you can “handle” and what might change things up for you. This is what I want to discuss in more detail.

Your temperature can be affected by many things, ranging from different individual metabolisms to whether you are fighting off an infection. These differences in temperature can be rather severe, or they can be small fluctuations that will vary hour by hour and day by day.

Temperature taking is an integral part of the sympto-thermal method and many things have to be taken into account when taking and interpreting your temperature in order to get an accurate picture of your fertility. Thankfully, there is no reason to avoid anything at first, just have in mind what may change your temperature and note it on your chart.

The temperature sign will not only tell you that ovulation occurred, but it can also help people in determining things such as low progesterone, hypothyroid, short luteal phases, or smaller issues such as a low-grade infection.

In order to take an accurate temperature one must do a few things:

1. Temperature must be taken after about 3-5 hours of sleep in order to insure that mind and body activity did not alter the temperature significantly. Some people seem to do fine with only 1 hour. Again, you be the judge, it’s your body!
2. The temperature must be taken in the same place, such as orally or vaginally, since different parts of the body maintain different temperatures, you will want to make sure that you only change the “location of collection” in between cycles.
3. Temperatures must be taken with the same thermometer, because different thermometers have slight differences in temperature read out. Thermometers can be changed in between cycles. See how to choose a thermometer here.
4. The time that you take your temperature should be kept consistent throughout a cycle. You can generally easily get away with plus or minus one hour and not have any issue. This time can also be changed at a new cycle or after ovulation has been confirmed.

Things that can make your temperature “off”

In order to rule out any confounding factors in a odd temperature, one must be familiar with the things that can affect a basal body temperature. There are the obvious and the not so obvious. These include:

• Fever
• Infection
• Certain drugs and medications
• Metabolism changers (excitement, physical or emotional stress)
• Alcohol
• Smoking (for 20 minutes or so after your last smoke)
• Sleep disturbances (insomnia, night walking, poor sleep, upsetting dreams)
• Jet lag
• A change in climate or room temperature
• Sleeping cuddled with someone if you usually do not
• Sleeping with an electric blanket or heating pad if you usually do not
• Sunburn
• Sleeping with your mouth open
• A recent discontinuation of hormonal contraceptives

Even without any of these confounding factors, basal body temperature is a dynamic thing! Your temperature will go up and down on a daily basis, but is still a useful tool in determining fertility. After ovulation, the basal body temperature will jump enough that there is a clear rise from pre-ovulatory levels. (Remember this is AFTER ovulation and you can not determine when ovulation will happen with your basal temperature, but only that it has, in retrospect). If the whole chart is taken into consideration you will not have a problem determining the shift that your temperature makes.

There are other big factors to notice when looking at your temperature. Elevated temperatures could be hyperthyroid, and low temperatures likely indicate hypothyroid. Small variations in different individuals temperatures can also be attributed to general body metabolism, which can vary slightly in healthy individuals. In addition, you can generally see a progesterone deficit if the temperature raises slowly after ovulation, temperatures dip onto or below the cover line, or luteal phases are less than 10 days. In addition, if there is no temperature shift it is almost definitely a sign that the person is not ovulating (with very few exceptions).

Overall, taking a basal body temperature is a useful tool for you if you want to know more about your fertility. I know the list of things that can change your temperature looks a little intimidating, but for most people their temperature is changed minimally or not at all. I always recommend that my clients just take their temperature for a cycle, note anything they think may have made it funky, and figure out what makes a difference for them. These are things that should be kept in mind when interpreting a chart, rather than worried about. You may be more or less sensitive to certain factors and only through taking your temperatures can you find out what you can tolerate to get a readable chart, and in doing so you may notice that it is easier than you think!