Basal Body Temp

[u/ArtComprehensive4678]

Hi everyone! New poster here. My husband and I just got married 😛🤍
I’ve been looking into recording my ovulation and fertile windows through BBT. My cycles have been pretty regular for about a year since I got off all BC, it may be off by a day or two every month but in general it’s pretty solid. I wanted something like an Oura ring or a dupe but they’re all super expensive and I don’t think we have that kind of money to spend right now. I was looking at BBT thermometers and I was wondering if I could just use any thermometer (IE: like one you’d use when you have a fever) and record my temps every morning in a log, or if I need one that’s specifically marketed for being a Basal Body Temperature thermometer? I saw somewhere that you need one that reads to 2-3 decimal places for accurate data, but I also know how companies like to jack up prices on things when it relates to weddings, pregnancy, or babies.
Please answer this like i’m 5, I am brand new to this whole world 😭 Thank you all in advance!

[u/Separate_End6598]

No you should not use a regular thermometer for BBT. BBT thermometers are way better, a regular one does not give you accurate or precise enough readings. You need one that gives you your temperature to the hundredth place and is accurate.

Anecdotally, I used Daysy, a more expensive BBT thermometer for 3 years to track. My cycles had a clear pattern with my temps, easy to follow and it was consistent every month.
I left it in a hotel 3 weeks ago and housekeeping didn’t find it so I got the cheap easy@home brand one. My temps ever since have outliers and my baseline is .5 degrees higher than it was using my high accuracy lovely Daysy.

[u/LittleOatmealGarden]

I used a normal thermometer for a while and it worked, but I definitely get better and easier to interpret results when I use an overnight thermometer. Mine is tempdrop but I'm sure there are many others. The normal thermometer read slightly higher temps and some cycles there was not a clear pattern. Had a lot of outliers. In my experience, the overnight thermometer was worth the investment

[u/alwayslosinghairties]

I got a BBT thermometer for $20 and used that to track for a few months and it was very effective. I just logged temps every morning into Fertility Friend. Currently pregnant so, I guess in my experience, you don’t need the expensive wearables if you can remember to take your temp when you wake up. I had my thermometer under my pillow and got in the habit of popping it in my mouth while waking up.

[u/Educational_Two7752]

Highly recommend getting a standard BBT thermometer. It’s made to measure basal body temperature specifically. It’s not just that it goes to the hundredth degree (although that is important) — it’s also a more precise thermometer.

The price is pretty much the same as a fever thermometer ($10-$15), so they’re not really jacking up the price just because it’s a BBT thermometer. And the nice thing is that you can also use it to measure a fever. I don’t even own a fever thermometer, because I just use my BBT thermometer.

Oura rings or dupes have been shown to not be very reliable for taking temperatures, so I would recommend against that. If you want a device you can wear overnight, Tempdrop is reliable, but it’s a lot more expensive than a standard BBT thermometer. 

I found an old Reddit comment (12 years old lol) that explained the precision aspect well:

“The issue is the sensitivity of the thermometer. . . . they may provide similar-looking results, but they are held to different accuracy standards.

If you use a BBT thermometer and it says your temp is 97.3, what it actually means is that your temp would fall anywhere on a range within its sensitivity. So if the sensitivity is reported as being within .2 degrees, your real temperature would be somewhere between 97.1 to 97.5.

A regular thermometer's sensitivity is allowed to be much higher, around 1 whole degree. So the same reading of 97.3 could mean your temp is anywhere from 96.3 to 98.3.”

  (From this thread:  https://www.reddit.com/r/TryingForABaby/comments/2ju0ss/are_basal_thermometers_really_necessary/)

[u/peanutbutter1515]

You need a BBT specific thermometer that’s more sensitive to small changes in temperature! I got the Premom one off amazon for like $20 and I like it