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~ Addtional BBT Tips (from FertilityFriend.com)

Some important guidelines to follow when taking your BBT

Your temperature data will be most reliable if you follow these guidelines. Not following these guidelines may make your chart difficult to read and may make detecting ovulation more difficult as well. It is essential that you use a special BBT thermometer and that you take your temperature in the morning right after waking. Please note that these are ideal guidelines. We recognize that the realities of your life may make meeting these ideals difficult or impossible at times. Fertility Friend is able to detect ovulation and make its analysis even under less than ideal conditions. The closer you can get to the ideal, the more accurate and reliable your ovulation detection, analysis and interpretation will be.

  • Take your temperature before rising in the morning as any activity can raise your BBT.
  • If you use a mercury thermometer, shake it down the previous night. (Or ask your partner to do it)
  • Take your temperature at the same time every morning.
  • Take your temperature after at least 3 consecutive hours of sleep.
  • Keep your thermometer accessible from your bed so you do not have to get up to get it.
  • Use the same thermometer throughout your cycle if possible. If it breaks or the battery dies and you use a new one, make a note of it on your charts.
  • Keep a spare thermometer in case one breaks (especially if you are using a glass thermometer).
  • Temperatures can be taken orally or vaginally but must be taken in the same place throughout the cycle since the temperatures of the different parts may vary. Most women prefer to take their temperatures orally and this is usually fine, though some women find that they get a clearer reading by temping vaginally.
  • Record your temperature soon after you take it (or ask your partner to) since most thermometers only store a reading until the next use. If you have to do something else or want to stay in bed, you can record it later, but we recommend recording it right away when possible to avoid forgetting. Fertility Friend includes a printable bedside notepad in case you are not able to log in right away.
  • If you must use a heating pad or electric blanket, keep it at the same setting throughout your cycle. Make a note of its use.
  • Take your temperature before doing anything else including eating, drinking or going to the bathroom. If circumstances arise that prevent you from taking your temperature right away, take it as soon as you are able and make a note of the circumstances.
  • If you have special circumstances on a temporary or an ongoing basis and you are unable to follow all of the above guidelines, keep temping anyway following the guidelines as closely as possible. Make a note of your special circumstances in the notes section of your chart and/or in your charting profile and Fertility Friend and our team will do our best to interpret your chart. There is still a good chance that you will be able to chart and see your fertility pattern.
  • Enter your temperature and always record the time you took it in the data entry page on Fertility Friend. The time you took your temperature is also important for the analysis.

Factors that can influence your BBT

As with your cervical fluid, there are certain factors that can influence your basal body temperature. These should be noted in the notes section of Fertility Friend. Again, as with the factors that influence cervical fluid, these factors will usually not make charting and chart analysis impossible, especially if they occur only rarely, though it may be more challenging. In most cases, even when these factors apply on an ongoing basis, they will not skew your data so much that reading the chart is impossible. It is important to make a note of the factors, however to help with the interpretation of the chart. The following factors may influence your BBT:

  • fever
  • illness and infections (even those that do not produce a fever)
  • cold, sore throat
  • drugs and medications
  • alcohol (especially in large quantities, though all alcohol consumption should be recorded)
  • smoking (if you smoke, you should consider quitting before you are even pregnant)
  • emotional stress
  • physical stress
  • excitement
  • sleep disturbances (insomnia, night-waking, upsetting dreams, poor sleep)
  • change in waking time
  • jet lag
  • travel
  • change of climate
  • use of electric blanket
  • change of room temperature
  • discontinuing birth control pills
  • breastfeeding

We recommend entering your temperature data as early as you can in the morning before you get caught up in the routine of your day. It is much easier to remember when it is a habit and your thermometer will likely only store your reading for one day. If you are unable to log into Fertility Friend right away, record your observations on paper until you are able to log in. A printable bed side notepad is provided for this purpose. If you have questions about your BBT pattern or are wondering about your specific circumstances, you can write to the Fertility Friend Team at any time for advice, encouragement or an evaluation of your chart.
More about BBT

Different Waking Times

One or two temperatures taken at different times during your cycle should not have too much impact on your chart especially if they are not close to ovulation time. Normally there is no need to adjust your temperature. If you want to use the temperature adjuster once or twice when it is not too close to ovulation, that should not pose a significant problem. More than a couple of temperatures taken at different times, however, can adversely effect the interpretation of your chart. You should try to avoid using the temperature adjuster if possible since adjusted temperatures are not nearly as accurate as those you record daily at the same time. You may find it useful to set an alarm so that you can take your temperature at the same time every day. You can just take your temperature and go right back to sleep if you do not have to get up right away. If your partner gets up at the same time every day, you can ask to be briefly woken up so you can take your temperature. Your BBT thermometer will store the reading for you until you can record it.

Night Waking

If you have to get up in the night and it is unavoidable, like having to take care of a small child, or if you have to go to the bathroom, just do the best you can. Take your temperature as close as you can to the same time each morning and choose a time that is likely to be when you have had the most sleep. For example, if your toddler wakes up every morning at 6 am, then take your temperature at that time, even if you go back to sleep. Try to avoid taking your temperature in the middle of the night, though, even if you seem to always get up at the same time in the middle of the night. Temperatures taken in the morning show a clearer biphasic curve and the time is more predictable.

Multiple Temperature Readings

Taking your temperature more than once can cause unnecessary confusion. We really recommend that you only take your temperature once and go with that one. If you wake up in the middle of the night or earlier than your usual wake up time and you know you are going back to sleep, resist the urge to take your temperature. If you do take your temperature twice (or more) then choose the temperature that was taken closest to the time you usually take it. The only good reason for taking your temperature more than once is if you wake up early and you do not know if you will be able to get back to sleep. If you did not go back to sleep, choose the temperature right after you woke up. If you have two temperatures taken before and after your regular wake up time and you slept before both of them, then you can use the temperature adjuster to give you an adjusted temperature. Try to avoid this though, as relying too heavily on it can adversely effect the interpretation of your chart.

Shift Work

It is not impossible to take your BBT if you work shifts, but it will be more challenging. Take your temperature at the time you wake up when you are most likely to have had the most sleep. Be as consistent as you can. On your days off, take your temperature after you wake up as well, even if it is at a different time. Make a note on your chart of changes in your waking schedule. You may take your temperature in the afternoon before you go to work if that is your usual waking time and the time after which you are most likely to have had the most sleep. It is not useful to take your temperature when you are already awake and active.


If you travel within your own time zone, just keep on taking your temperature at the same time. You may notice a slight fluctuation if the climate is warmer/colder but this should not have a huge impact on your chart. Make a note in the notes section that you were traveling so you can explain unusual temperature patterns. If you are traveling to a different time zone, the disturbance is usually only limited to the day of travel and the day after. Keep taking your temperature as before, using the same time in the local time. We recommend not adjusting any temperatures, but again, make a note of the circumstances. Unless you are traveling right around the time of ovulation, you should still be able to discern your pattern. When BBT is less reliable because of such a special circumstance, pay extra close attention to your other fertility signs to avoid missing a potential fertile opportunity.

Daylight Saving Time

The effect of Daylight Saving Time (DST) on your temperature is usually limited to the day of the change because you adjust quite quickly. In addition, the exact effect depends strongly on your own metabolism. Some people will see no effect at all while others will see a slight change (increase or decrease). Because in general having one temperature slightly off will not change your chart interpretation, Fertility Friend's recommendation is to record your temperature as usual without correcting it in any manner. We recommend that you keep taking the temp at the same time. If you took it at 6 in the morning before the change, then take it at 6 in the morning after the change.

Erratic Temperatures

If your temperatures are erratic, the first thing you should do is review the guidelines about taking your BBT and make sure you are using a special basal body temperature thermometer. If you are following the guidelines (taking your temperature at the same time each morning, before getting up and using a BBT thermometer) and still have erratic temperatures, the first thing to do is review your data to see what could be disturbing the temperature. You may also consider changing your thermometer or replacing the battery in your thermometer to see if this helps. You may also want to talk to a Fertility Friend guide to get her opinion about what could be causing the erratic temperatures. If you have several cycles that are erratic and you are taking and recording your BBT properly, and you are unable to see an ovulation pattern, you should talk to your healthcare provider.

"Flat" Temperatures

If your temperatures seem to be around the same level all the time, the culprit is usually your thermometer. Even when you are taking your temperature at the same time, following all the guidelines, there is usually some fluctuation in temperatures. Your first step is to check your thermometer's battery or get a new thermometer. If your temperatures are still flat, and/or show no sign of a biphasic (ovulatory) pattern when you would expect them to, this is something to ask your doctor about if it happens for a few cycles.

Timing Intercourse using BBT

By the time you see a rise in temperature, you have probably already ovulated and it may be too late to time intercourse for conception purposes. You should still have intercourse though until ovulation is confirmed by a sustained rise in temperatures. You can predict ovulation, however, based on when you ovulated in previous cycles as pinpointed with your BBT and other fertility signs. The best thing to do is to follow the Fertility Analyzer in Fertility Friend which takes into account all signs and previous cycles as well.