pinksprinkles
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This post has been edited to include much more information for new BnB members and those who want to understand ovulation more fully. It now also contains a comparison of BBT Thermometers at its conclusion. I hope you enjoy the read. The title was changed multiple times on the original post, causing bookmarks for the page to no longer work. Please update to this link.
There are a lot of you out there! Every day I see many posts from ladies who are trying to figure out what is going on "in there". Usually, I go thread by thread having a very similar discussion with each of you wonderful women. I have often thought about writing a "cut and paste" answer, but I did not feel that that would honor the connection that we all have with each other here on BnB.
This post is meant to summarize what I have learned while studying BBT in relation to women's reproduction into a concise, helpful answer. The main thing I'd like to say, is that if you want to know for sure if you've O'd you can chart your Basal Body Temperature, or BBT!. For many women, charting will tell you exactly what is happening in there! You can usually pinpoint O to the day! It is simple. It is easy. And it will save you loads of stress.
No matter what your Cervical Mucus (CM), no matter your Cervical Position (CP), no matter your spotting, no matter your cramps, and no matter your normal cycle length- there is no way to know if you have O'd or not without a chart of your BBT. Only your BBT thermometer is going to be able to tell you that!
If you need help identifying possibly Ovulation times, and you haven't charted your BBT yet, don't fret! All the ladies on this board can help guess at your possible O date, and we will all offer our best advice. We will all offer words of wisdom from our own lives.
If you really do want to know if you O'd or not, BBT is the only way to know for sure.
I know temping can sound a bit overwhelming at first, or maybe you just don't know much about it and don't know where to go for in-depth info- those are things I hear frequently. And they are valid concerns! In this post I want to show you that temping is quick, it's easy, and it delivers a wealth of knowledge. Knowledge that is easily understood if you're given the tools you need. Hopefully, this post will help you in figuring out the basics of temping and get you to a place that you are more comfortable with the idea!
(Disclaimer (addressing some original post issues): I do realize that temping doesn't work for everyone and there are definitely ladies out there who are unable to temp- but for many women, temping can be a wonderful tool: This post is for those women.)
Charting your BBT will save you a world of stress. It will leave you feeling empowered and in control of your body. It will let you know that you are BD'ing on the right day. It will help you figure out mid-cycle spotting. If at some point you do need to go to your doctor to try to figure out fertility issues down the road, your charts are going to be very helpful. (This is how I started charting! My doctor wanted to know what was happening in my cycle and said, "Jamie, go pick up a BBT thermometer! Let's figure out what's going on in there!") It turns out that if you chart, you can actually show your OB/Gyn when you are ovulating, what your body is doing, when it's maybe not doing what you'd like. You're pretty much saying, "This is important to me and I've taken the time to do my bit." And it only costs about $10 for a BBT thermometer.
For all the hoopla and gadgets and everything else that goes along with TTC that we spend money on, at the bare bones of it all, $10 is al you need to know what is going inside your body, how long your luteal phase is, if you're BD'ing at the right time, etc, etc, etc. Now your BBT isn't going to tell you when you are going to O, that's what OPK's are for. But, it will tell you if you have. Which is great, because a positive OPK doesn't mean you have O'd- it means your body will try to O. It may fail. You may have to BD again later in the cycle. I have had cycles where I had four separate LH surges (positive OPK's), each several days apart before my body actually O'd!
Many of us have wondered if we're skipping a cycle, O'ing at all, wondering why we're not pregnant yet. Maybe you've been TTC for 4 months and you are starting to doubt your own fertility! All of the pressure us ladies go around putting on ourselves is unhealthy and many times unnecessary- and that is why I so highly recommend charting your BBT.
Reasons to Temp:
1. To cut down on stress associated with TTC.
2. You know when/if you've O'd.
3. You might have an idea about what some mystery spotting means.
4. You'll know if you're having sex (BD'ing) on the right days.
5. You can bring the charts to your doctor if you're having reproductive/fertility issues.
6. You will know when to expect your period.
7. You will know more about your personal cycle.
8. Over time, you'll have the ability to notice if something is "not right" in your cycle. In some cases this means early diagnosis of infection/disease/etc. Early detection of women's reproductive illnesses saves lives!
There are many other reasons to temp, but I find these to be some of the best!
Guys have it so easy. They just produce their little swimmers at a constant rate, squirt them out on occasion, continue making some more. Not a lot going on there for the average guy! But for us women, things are nowhere near so cut and dry. We're ever changing tides of hormones, chemical, surges, and plateaus. We change every day as our bodies prepare to nurture a sticky little bean if one happens to come along and snuggle up for a nine month journey, and clean up and redecorate the "nursery" if it doesn't. With so much going on in there, it's hard to know what's happening most of the time, but, when you strip it down to the bare bones, our cycles can usually be accurately displayed in our BBT's.
BBT is determined by the chemicals in our bodies. Different hormones cause our temperature to change throughout our cycles.
At the onset of our periods, we become a blank slate of chemicals. As we approach O, our estrogen levels rise. Rising estrogen lowers our temperatures as we approaching ovulation, as well as causes changes in our cervical position and our cervical mucous. Estrogen, in conjunction with Luteinizing Hormone (generally refereed to as LH), also causes softening and subsequent dialation of the cervix to allow sperm to enter.
Estrogen also LOWERS our temperatures!
During the pre-O phase, and while the estrogen level of our bodies rises, our ovaries grow many follicles each developing an egg. When the LH surges into our system, our body begins the process of ovulation. From the onset of LH, it takes about 24-48 hours to build up to O. At that point, as one of the follicles bursts open, it releases an egg. At the same time, the luteinizing hormone transforms that follice into something new! The Corpus Luteum!
During the LH surge, just before O, we may notice a DIP in temperature!
For the next 10-16 days, the Corpus Luteum will be in charge of Progesterone production (along with slight amounts of estrogen). Progesterone is the hormone that says "Hey! There's an egg out there and we need to see if it will get fertilized or not! Batten down the hatches! Don't let that period start yet!"
Progesterone also RAISES our temperatures!
For the next week, the released egg goes on qute a journey. As the hormones in our bodies cause tiny, soft hairs in our fallopian tubes to brush the egg down, and finally into, the uterus, the uterine lining continues to thicken and prepare for implantation. If fertilized and able, the egg will implant in the uterus.
If the egg has been fertilized and does implant, the egg sends a message to the Corpus Luteum to keep going! The Corpus Leteum says "Woohoo!" and continues the production of progesterone. It will keep up progesterone production until the placenta establishes itself and begins hormone regulation. You will notice your temperature stay elevated throughout your pregnancy!
When the Corpus Luteum receives the signal (Woohoo!) we may notice a DIP in our temperature.
After the dip, some women notice a 2nd RISE in temperature to a level they would not normally see if they were not pregnant!
If the egg does not implant, the Corpus Luteum dies, Progesterone levels fall, and the mean old shows up for a visit! (aka: our periods begin.) This marks the beginning of a new cycle.
If we do not become pregnant, Progesterone falls and our temperature LOWERS.
At the begining of our cycle, estrogen builds and our temps are LOW. At the LH surge, our temperature may DIP as we prepare to O. After O, the progeseterone produced by the Corpus Lutem causes out temperatures to RISE.
If we are pregnant, we may notice a DIP or RISE (or both) in our temps. Our temperature will stay elevated throughout pregnancy.
If we are not pregnant, out temps will fall. This is when menstruation occurs.
Please check out my August 2011 Chart chart at Fertility Friend. (You will need to scroll down.)
My August chart shows a pretty standard BBT flow with LOW PRE-O TEMPS, an OVULATION DIP, HIGH POST-O TEMPS, and FALLING PERIOD TEMPS.
Now that you understand how your BBT works, the hard part is over! Now all you need to do is temp and chart. Here is a step by step guide to temping:
1. Pick up a BBT thermometer. The BD Basal on Amazon is the most accurate BBT thermometer on the marker. If you are able to order it, that is the one to get. It is accurate to .1F. The Wallgreens thermometer comes in at a close second at somewhere between .09 and .16 degree accuracy. (it measures in C and converts to F, actual accuracy is unknown but somewhere in the given range.) I use the Walgreens BBT thermometer as it was easier and faster to acquire. The new CVS thermometer offered on their website is NOT recommended.
2. Start a chart. Most women on BnB use Fertility Friend. I recommend it because it is easy to link to you chart. (Simply go to Sharing -> Setup to get your chart code.) Also, since so many women on here use it, we'll always be able to help you decipher what your chart says!
3. Choose you temping method. You can temp orally if you prefer, but vaginal temping will usually give better results. (Your mouth can very much more easily depending on room temp, mouth breathing, etc.) Whichever you choose, you must stick with it for the entire cycle because vaginal temps are warmer than oral temps- and switching mid-ycle will mess up your chart.
4. Choose your temping time. You must chart at the same time everyday before you get out of bed or move around at all. If you wake up at the exact same time everyday, temp then. If you wake up at different times every day figure out when the best temping time is and set an alarm. IE: I generally get up somewhere between 8:30am and noon, depending on the day. But I hardly ever have to be up before 8:30. And I'm always in bed by 5a. Since an accurate BBT requires 3 hours of sleep before temping I set my alarm clock for 8:30. Many mornings, I temp, and then go back to sleep.
5. Temp and Record. Temp each morning and record it on your chart. The first month might be confusing, but looking back on your temps, you should be able to notice when different hormones were running the show.
6. Be excited! You now have a much deeper understanding of your body than many women out there. Feel empowered by that knowledge!
Charting your Cervical Position, Cervical Mucus, and other signs and symptoms can enhance you charting experience as well as help you to know when to Baby Dance (Often seen on BnB as "BD", aka, have sex). If you use Fertility Friend, you can check out the charting guides. There is an entire lesson plan built into the site that very simply explains how to go about charting all of your different symptoms.
Even if you are only charting your BBT, I highly recommend going throught the Fertility Friend lessons. The lessons will simply and easily go through what to expect when analyzing your temps as well as explain the amazing features built in to the site. You will be very glad you took the time to go through them.
As mentioned earlier, the first month may be confusing, but don't give up! After a few cycles, you'll never again have to guess if you have O'd. You can leave the guessing where is belongs: the infamous Two Week Wait! (2ww, or tww)
AND now you can share your chart with others. Go on and post it in your signature on BnB. Simply click on the BnB "quick Links" in your menu bar and go to "Edit Signature". You can put the link from your FF "Share Page" in there!
I hope this post helps you to take charge of your fertility! And I hope it leaves you feeling empowered with the knowledge that yes, you can know what's going on "in there"!
~*BBT THERMOMETER COMPARISON*~
CVS BBT THERMOMETER
I ordered the CVS purple thermometer off their site this past week to check out and when it arrived it turned out to be a different (white) thermometer. I did call up CVS and bring it to their attention and they said they'd get the website fixed as soon as possible. The rep I spoke to doesn't think that they are carrying the purple one any more.
As for the new white thermometer, it has some serious issues:
1. It continues to read your temp after it beeps to say it is done. (I had it "beep" at 98.3-ish, but then it kept temping up to around 98.9!)
2. The thermometer is VERY short. I temp vaginally and was having a hard time getting the thermometer to the correct depth without it disappearing. (Sorry for tmi.)
3. I used it three times in a row (all about 2 minutes apart) and got three VERY different readings- all at least .2 degrees apart. Eep!
BD Basal is the only thermometer I feel confident in recommending you buy at this time. The BD Basal looks to be the best thermometer out right now (accurate to .1F, the accuracy recommend by the book Taking Charge of your Fertility) and it can be found on Amazon.
I also looked into the Walgreens BBT issue.
The concern so far is that the Walgreens and Walmart BBT have been displaying "repeat" temps. From what I've discovered, this is probably not true. What's appears to be going on is that the thermometers measure in C, not F, and convert to F temps. Since C is less "accurate" than F (because C measures in a rougher gradient), the conversions come across as what folks have been calling "repeat temps", but they're just the conversions of C, and just as accurate as their C counterpart. If true, this may make the Walgreen BBT more accurate than the BD Basal, coming in at somewhere between .09F (more accurate) and .16F (less accurate) accuracy. However, this is speculation. And I do not recommend buying this thermometer based off speculation.
NOTE: Some women notice that they sometimes get temps that are not .09-.16F apart. It is theorized that the thermometer may ALSO be checking for .1 degree accuracy F readings, and displaying them if they are closer to the actual temp than the C conversion would be. If this is the case, it would make the Walgreens/Walmart BBT more accurate than the BD Basal.
BD BASAL is the best choice for new charters as it has a published accuracy and in easy to understand. However, those ladies already charting with Walgreens/Walmart BBT thermometers need not switch if they have not noticed any issues. That being said, since there have been some issues with Walgreens thermometers in the past, I would not recommend buying one.
DEAR "DID I O?" LADIES
There are a lot of you out there! Every day I see many posts from ladies who are trying to figure out what is going on "in there". Usually, I go thread by thread having a very similar discussion with each of you wonderful women. I have often thought about writing a "cut and paste" answer, but I did not feel that that would honor the connection that we all have with each other here on BnB.
This post is meant to summarize what I have learned while studying BBT in relation to women's reproduction into a concise, helpful answer. The main thing I'd like to say, is that if you want to know for sure if you've O'd you can chart your Basal Body Temperature, or BBT!. For many women, charting will tell you exactly what is happening in there! You can usually pinpoint O to the day! It is simple. It is easy. And it will save you loads of stress.
BUT WAIT! DID I "O"?
No matter what your Cervical Mucus (CM), no matter your Cervical Position (CP), no matter your spotting, no matter your cramps, and no matter your normal cycle length- there is no way to know if you have O'd or not without a chart of your BBT. Only your BBT thermometer is going to be able to tell you that!
If you need help identifying possibly Ovulation times, and you haven't charted your BBT yet, don't fret! All the ladies on this board can help guess at your possible O date, and we will all offer our best advice. We will all offer words of wisdom from our own lives.
If you really do want to know if you O'd or not, BBT is the only way to know for sure.
I know temping can sound a bit overwhelming at first, or maybe you just don't know much about it and don't know where to go for in-depth info- those are things I hear frequently. And they are valid concerns! In this post I want to show you that temping is quick, it's easy, and it delivers a wealth of knowledge. Knowledge that is easily understood if you're given the tools you need. Hopefully, this post will help you in figuring out the basics of temping and get you to a place that you are more comfortable with the idea!
(Disclaimer (addressing some original post issues): I do realize that temping doesn't work for everyone and there are definitely ladies out there who are unable to temp- but for many women, temping can be a wonderful tool: This post is for those women.)
CHARTING YOUR BBT
Charting your BBT will save you a world of stress. It will leave you feeling empowered and in control of your body. It will let you know that you are BD'ing on the right day. It will help you figure out mid-cycle spotting. If at some point you do need to go to your doctor to try to figure out fertility issues down the road, your charts are going to be very helpful. (This is how I started charting! My doctor wanted to know what was happening in my cycle and said, "Jamie, go pick up a BBT thermometer! Let's figure out what's going on in there!") It turns out that if you chart, you can actually show your OB/Gyn when you are ovulating, what your body is doing, when it's maybe not doing what you'd like. You're pretty much saying, "This is important to me and I've taken the time to do my bit." And it only costs about $10 for a BBT thermometer.
For all the hoopla and gadgets and everything else that goes along with TTC that we spend money on, at the bare bones of it all, $10 is al you need to know what is going inside your body, how long your luteal phase is, if you're BD'ing at the right time, etc, etc, etc. Now your BBT isn't going to tell you when you are going to O, that's what OPK's are for. But, it will tell you if you have. Which is great, because a positive OPK doesn't mean you have O'd- it means your body will try to O. It may fail. You may have to BD again later in the cycle. I have had cycles where I had four separate LH surges (positive OPK's), each several days apart before my body actually O'd!
Many of us have wondered if we're skipping a cycle, O'ing at all, wondering why we're not pregnant yet. Maybe you've been TTC for 4 months and you are starting to doubt your own fertility! All of the pressure us ladies go around putting on ourselves is unhealthy and many times unnecessary- and that is why I so highly recommend charting your BBT.
Reasons to Temp:
1. To cut down on stress associated with TTC.
2. You know when/if you've O'd.
3. You might have an idea about what some mystery spotting means.
4. You'll know if you're having sex (BD'ing) on the right days.
5. You can bring the charts to your doctor if you're having reproductive/fertility issues.
6. You will know when to expect your period.
7. You will know more about your personal cycle.
8. Over time, you'll have the ability to notice if something is "not right" in your cycle. In some cases this means early diagnosis of infection/disease/etc. Early detection of women's reproductive illnesses saves lives!
There are many other reasons to temp, but I find these to be some of the best!
THE NITTY-GRITTY, or HOW IT ALL WORKS
Guys have it so easy. They just produce their little swimmers at a constant rate, squirt them out on occasion, continue making some more. Not a lot going on there for the average guy! But for us women, things are nowhere near so cut and dry. We're ever changing tides of hormones, chemical, surges, and plateaus. We change every day as our bodies prepare to nurture a sticky little bean if one happens to come along and snuggle up for a nine month journey, and clean up and redecorate the "nursery" if it doesn't. With so much going on in there, it's hard to know what's happening most of the time, but, when you strip it down to the bare bones, our cycles can usually be accurately displayed in our BBT's.
BBT is determined by the chemicals in our bodies. Different hormones cause our temperature to change throughout our cycles.
At the onset of our periods, we become a blank slate of chemicals. As we approach O, our estrogen levels rise. Rising estrogen lowers our temperatures as we approaching ovulation, as well as causes changes in our cervical position and our cervical mucous. Estrogen, in conjunction with Luteinizing Hormone (generally refereed to as LH), also causes softening and subsequent dialation of the cervix to allow sperm to enter.
Estrogen also LOWERS our temperatures!
During the pre-O phase, and while the estrogen level of our bodies rises, our ovaries grow many follicles each developing an egg. When the LH surges into our system, our body begins the process of ovulation. From the onset of LH, it takes about 24-48 hours to build up to O. At that point, as one of the follicles bursts open, it releases an egg. At the same time, the luteinizing hormone transforms that follice into something new! The Corpus Luteum!
During the LH surge, just before O, we may notice a DIP in temperature!
For the next 10-16 days, the Corpus Luteum will be in charge of Progesterone production (along with slight amounts of estrogen). Progesterone is the hormone that says "Hey! There's an egg out there and we need to see if it will get fertilized or not! Batten down the hatches! Don't let that period start yet!"
Progesterone also RAISES our temperatures!
For the next week, the released egg goes on qute a journey. As the hormones in our bodies cause tiny, soft hairs in our fallopian tubes to brush the egg down, and finally into, the uterus, the uterine lining continues to thicken and prepare for implantation. If fertilized and able, the egg will implant in the uterus.
If the egg has been fertilized and does implant, the egg sends a message to the Corpus Luteum to keep going! The Corpus Leteum says "Woohoo!" and continues the production of progesterone. It will keep up progesterone production until the placenta establishes itself and begins hormone regulation. You will notice your temperature stay elevated throughout your pregnancy!
When the Corpus Luteum receives the signal (Woohoo!) we may notice a DIP in our temperature.
After the dip, some women notice a 2nd RISE in temperature to a level they would not normally see if they were not pregnant!
If the egg does not implant, the Corpus Luteum dies, Progesterone levels fall, and the mean old shows up for a visit! (aka: our periods begin.) This marks the beginning of a new cycle.
If we do not become pregnant, Progesterone falls and our temperature LOWERS.
TEMPERATURE SUMMARY
At the begining of our cycle, estrogen builds and our temps are LOW. At the LH surge, our temperature may DIP as we prepare to O. After O, the progeseterone produced by the Corpus Lutem causes out temperatures to RISE.
If we are pregnant, we may notice a DIP or RISE (or both) in our temps. Our temperature will stay elevated throughout pregnancy.
If we are not pregnant, out temps will fall. This is when menstruation occurs.
Please check out my August 2011 Chart chart at Fertility Friend. (You will need to scroll down.)
My August chart shows a pretty standard BBT flow with LOW PRE-O TEMPS, an OVULATION DIP, HIGH POST-O TEMPS, and FALLING PERIOD TEMPS.
TAKING YOUR BBT
Now that you understand how your BBT works, the hard part is over! Now all you need to do is temp and chart. Here is a step by step guide to temping:
1. Pick up a BBT thermometer. The BD Basal on Amazon is the most accurate BBT thermometer on the marker. If you are able to order it, that is the one to get. It is accurate to .1F. The Wallgreens thermometer comes in at a close second at somewhere between .09 and .16 degree accuracy. (it measures in C and converts to F, actual accuracy is unknown but somewhere in the given range.) I use the Walgreens BBT thermometer as it was easier and faster to acquire. The new CVS thermometer offered on their website is NOT recommended.
2. Start a chart. Most women on BnB use Fertility Friend. I recommend it because it is easy to link to you chart. (Simply go to Sharing -> Setup to get your chart code.) Also, since so many women on here use it, we'll always be able to help you decipher what your chart says!
3. Choose you temping method. You can temp orally if you prefer, but vaginal temping will usually give better results. (Your mouth can very much more easily depending on room temp, mouth breathing, etc.) Whichever you choose, you must stick with it for the entire cycle because vaginal temps are warmer than oral temps- and switching mid-ycle will mess up your chart.
4. Choose your temping time. You must chart at the same time everyday before you get out of bed or move around at all. If you wake up at the exact same time everyday, temp then. If you wake up at different times every day figure out when the best temping time is and set an alarm. IE: I generally get up somewhere between 8:30am and noon, depending on the day. But I hardly ever have to be up before 8:30. And I'm always in bed by 5a. Since an accurate BBT requires 3 hours of sleep before temping I set my alarm clock for 8:30. Many mornings, I temp, and then go back to sleep.
5. Temp and Record. Temp each morning and record it on your chart. The first month might be confusing, but looking back on your temps, you should be able to notice when different hormones were running the show.
6. Be excited! You now have a much deeper understanding of your body than many women out there. Feel empowered by that knowledge!
EVEN MORE INFO!
Charting your Cervical Position, Cervical Mucus, and other signs and symptoms can enhance you charting experience as well as help you to know when to Baby Dance (Often seen on BnB as "BD", aka, have sex). If you use Fertility Friend, you can check out the charting guides. There is an entire lesson plan built into the site that very simply explains how to go about charting all of your different symptoms.
Even if you are only charting your BBT, I highly recommend going throught the Fertility Friend lessons. The lessons will simply and easily go through what to expect when analyzing your temps as well as explain the amazing features built in to the site. You will be very glad you took the time to go through them.
As mentioned earlier, the first month may be confusing, but don't give up! After a few cycles, you'll never again have to guess if you have O'd. You can leave the guessing where is belongs: the infamous Two Week Wait! (2ww, or tww)
AND now you can share your chart with others. Go on and post it in your signature on BnB. Simply click on the BnB "quick Links" in your menu bar and go to "Edit Signature". You can put the link from your FF "Share Page" in there!
I hope this post helps you to take charge of your fertility! And I hope it leaves you feeling empowered with the knowledge that yes, you can know what's going on "in there"!
~*BBT THERMOMETER COMPARISON*~
CVS BBT THERMOMETER
I ordered the CVS purple thermometer off their site this past week to check out and when it arrived it turned out to be a different (white) thermometer. I did call up CVS and bring it to their attention and they said they'd get the website fixed as soon as possible. The rep I spoke to doesn't think that they are carrying the purple one any more.
As for the new white thermometer, it has some serious issues:
1. It continues to read your temp after it beeps to say it is done. (I had it "beep" at 98.3-ish, but then it kept temping up to around 98.9!)
2. The thermometer is VERY short. I temp vaginally and was having a hard time getting the thermometer to the correct depth without it disappearing. (Sorry for tmi.)
3. I used it three times in a row (all about 2 minutes apart) and got three VERY different readings- all at least .2 degrees apart. Eep!
BD BASAL THERMOMETER
BD Basal is the only thermometer I feel confident in recommending you buy at this time. The BD Basal looks to be the best thermometer out right now (accurate to .1F, the accuracy recommend by the book Taking Charge of your Fertility) and it can be found on Amazon.
WALGREENS BBT THERMOMETER
I also looked into the Walgreens BBT issue.
The concern so far is that the Walgreens and Walmart BBT have been displaying "repeat" temps. From what I've discovered, this is probably not true. What's appears to be going on is that the thermometers measure in C, not F, and convert to F temps. Since C is less "accurate" than F (because C measures in a rougher gradient), the conversions come across as what folks have been calling "repeat temps", but they're just the conversions of C, and just as accurate as their C counterpart. If true, this may make the Walgreen BBT more accurate than the BD Basal, coming in at somewhere between .09F (more accurate) and .16F (less accurate) accuracy. However, this is speculation. And I do not recommend buying this thermometer based off speculation.
NOTE: Some women notice that they sometimes get temps that are not .09-.16F apart. It is theorized that the thermometer may ALSO be checking for .1 degree accuracy F readings, and displaying them if they are closer to the actual temp than the C conversion would be. If this is the case, it would make the Walgreens/Walmart BBT more accurate than the BD Basal.
CONCLUSION
BD BASAL is the best choice for new charters as it has a published accuracy and in easy to understand. However, those ladies already charting with Walgreens/Walmart BBT thermometers need not switch if they have not noticed any issues. That being said, since there have been some issues with Walgreens thermometers in the past, I would not recommend buying one.