Click here for a graph you can print out and chart your temperatures.

Digital Basal Thermometer


Basal Body Temperature is also called BBT; as we all know by now that web dwellers love abbreviations.  The fertility world is no different.  You can see a list of abbreviations commonly used in infertility HERE.

Basal stands for “base” and along with temperature refers to the temperature the body comes to when at rest.

If you have ever wondered why this reading is important it is because it is the constant that allows for charting to make sense.  By charting the BBT – Basal Body Temperature you can use this constant temperature when you awake each day to determine changes in your body.  So, basically put, finding a starting place can allow you to track your fertility before your life enters into a variable state throughout the day.

Some will tell you, with caution, that it “may” tell you if you are pregnant, ovulating or even cycling at all.  I think that you can tell everything AND nothing by charting using temps.   Let me explain that bold statement:

If you are faithful to charting your temps you will know exactly what YOUR body does and does not do.  If you are anovulatory (that just means you don’t ovulate) you will certainly grow tired of charting this way, but you will know that you did not have a dip before you ovulated and you will certainly see a rise if you do ovulate and conceive.  You will most likely see a dip on the day you conceive as well.

Simple stated; to ovulate you will need a rise in estrogen and to implant you will need a rise in estrogen as well; signaling the rise in hCG.  More on that in other articles found at

Let’s start at the beginning of the cycle:

Day 1 is the first day of bleeding.  No matter if you ended at day 25 or day 134 of your last cycle, day 1 is always the first day of bleeding.

These first temps are low because your body is producing FSH and Estrogen working hand in hand to “stimulate” your follicles to maturity; ie THE EGG.

Just before your body is ready to ovulate (again, it could be day 13 or day 130) your follicles stop being stimulated, your estrogen spikes, your temps drop to an even lower degree, the egg is released and you will see a spike.

Low temps around 96s are usually due to a low or Hypo-thyroid condition.  Temps in the low 97s are “normal” which really means, looks like you have a better chance, and higher temps can signify Hyperthyroid.  Pregnancy is the other possibility if you have light bleeding but maintain higher temps.  More on that later.

So, low temps like 97. 6, 97.4, 97.5, 97.6, 97. 6, 97.4, 97.5, 97.6, 97. 6, 97.4, 97.5, 97.6, 97.5 THEN…  hopefully, around the 14th day you see something like a downward spike or dip to maybe 97.2  You wait happily until the next day to see that your temps jump up, do an upward spike to about 97.8.  GREAT.

WORD OF CAUTION:    Will it look exactly like what I have typed above?  No, but if you see the pattern in YOU then you will see the pattern changes of YOU.  Now watch for another quick dip then rise around 6-8 days later.  This will be implantation but don’t worry if you don’t see it.  It is not always as easy to see this one.  Within this time though it is very important not to get careless;  keep up the good work and keep charting every day.

If you have not become pregnant, there will still be an ovulation spike.  This is just the egg’s own progesterone “oozing” into your system as it atrophies and dies.  But if you are pregnant, your progesterone will rise, your hCG will raise your temps and estrogen will also rise in order to begin preparing for the placenta to attach to the uterine lining and begin to prepare a “nest” for your little one.

One tip would be to try and rise at the same time every day as well.  Your body will fluctuate according to the time you rise by 1/10s of degrees.  Tony Weischler of Taking Charge of Your Fertility (in our bookstore) recommends this:

Add .1 degree (1/10) to your charting for every 1/2 hour EARLY you wake up and subtract .1 (1/10) for every 1/2 hour late you wake up.

Let’s make sense of why we would do this.

What you are trying to do is keep everything at a steady line.

If you base everything on a 24 hour period then you have a better chance of charting more accurate basal body temperatures because the variances will more easily show up.

Let’s look at what this would look like:

Wake up time Temperature 1/10s toadd/subtract Temperature to write on chart
7:00 97.4 0 97.4
7:00 97.5 0 97.5
7:30 97.5 - .1 97.4
7:00 97.5 0 97.5
6:30 97.3 + .1 97.4

The question now becomes what thermometer to use?  We only recommend Digital Basal Thermometers because they are accurate to the 1/10 degree.  What sense does it make to learn how to take your BBT – Basal Body Temperature if you do not have a Digital Basal Body Thermometer? If you compare, you will agree.

Digital Basal Thermometer


Consider also purchasing a journal for your fertility journey and keeping notes of anything that changes your  recordings such as being sick, a cold house etc.  You might even want to have a notebook or calendar specifically for these things.  I like using an Excel spreadsheet because you can play with all the variables and easily find averages and such. It automatically numbers the lines you are on as well so you don’t have to purchase expensive charting calendar software.

The leading authority on this subject remains Dr. Toni Weischler and below is a small part of what she has to say on the subject.  Hope this helps.  Contact us or read our other articles for more information to help you along the way.  Happy “baby making”.

Taken from the pages of  Taking Charge of Your Fertility

How to determine your temperature coverline:

1:  Identify the first day your temperature rises at least 2/10 of degree higher than it had been the previous 6 days.

2:  Highlight the last 6 temps before the rise.

3:  Locate the highest of those six highlighted temps.

4:  Draw the coverline 1/10 of degree above the highest of that cluster of six days preceding the rise.

5:  High temps during your period are irrelevant.

6:  Once you see a third high temperature above the coverline (the 3/10 higher than 6 preceding days) you know you have ovulated.

7:  For daylight savings time, take your temperature 20 minutes earlier Saturday 4/3, 20 minutes later Sunday 4/4 and then take temps normal time on Monday.

NOTE: Most NFP books will tell you that when you see above coverline temps for 18 days you are pregnant.

This article has been written by Brenda Albano of Whole Family Health and Infertility Workshop.

No part of it maybe copied without permission from the author.

Digital Basal Thermometer