BBT Charting accuracy

[luckymama]

well, well, ive been doing some research to check whether BBT charting is accurate, as sometimes i know i have ovulated like this cycle, but BBT kinda would suggest otherwise, i found this:

In 30 normally menstruating women, ages 19 to 41 (mean 24), gravida 0 to 5 (mean 0.7), basal body temperature (BBT) was correlated with serum luteinizing hormone (LH), progesterone, and estradiol or urinary estrogen levels assayed serially during one menstrual cycle. In 21 subjects (70%), a biphasic BBT correlated with an ovulatory hormonal pattern. Six women (20%) had a monophasic BBT but demonstrated a preovulatory estrogen peak, a midcycle LH surge, and a significant rise in serum progesterone levels during the luteal phase. The remaining three women (10%) showed anovulatory cycles (two women) or a deficient luteal phase (one woman) as determined by BBT and hormonal assays. The results indicate that in approximately 20% of ovulatory cycles the BBT failed to demonstrate ovulation.

so it works for most people doing BBT charting, but not necessarily for some people...

[luckymama]

and some more:

PIP: This study assesses how closely basal body temperature (BBT) charts match detailed endocrine data in distinguishing ovulatory from anovulatory cycles, detecting short or inadequate luteal phase cycles, and determining the time of ovulation. 6 experienced physicians were asked to separately evaluate 104 BBT charts representing 98 women between 18-30 years of age. These physicians were to evaluate each chart for the presence of a biphasic pattern and to estimate the day of ovulation that they thought showed a biphasic BBT curve. Accuracy of estimation was judged by comparison with the day of the luteinizing hormone (LH) peak. Results indicate that: 1) the number of charts for which each physician correctly estimated the time of ovulation +or- 1 day of the LH peak ranged from 24-34, 2) although each physician correctly estimated the time of ovulation from an average of 38.1% of the charts, only 9 (22.1%) of the charts were correctly assessed by all 6 physicians, 3) an additional 22.1% of these cycles were thought to have monophasic patterns, 4) 37 (48%) of the charts drew a mixed response from the physicians, whose judgements differed regarding the presence of biphasic patterns or the correct day of ovulation, 5) in the 18 charts evaluating the short luteal phase cycles, the day of ovulation was assessed correctly in only one cycle by 2 of the 6 physicians, and 6) the anovoluntary cycles were uniformly found to have monophasic patterns by all evaluators. Extreme caution in interpretation is urged when BBT is used for clinical or research evaluations of ovualtion or menstrual cycle dynamics.

very interesting really...i think i may stop temping as to stop causing myself uneeded worry, as i am certain i o'd.

what does everyone else think?
anyone gotten pregnant while charting, and not had a "perfect" chart, id love to hear your stories.

[chicken]

Doula - they are very interesting results. I'm on my first month of charting, so it will be interesting to see if I'm 'normal'. Have you thought about using OPKs as a back-up?

[luckymama]

na, i think ill def rely on saliva monitor, and checking CM and CP, it seems to work out right.

[chicken]

Everyone's got their preferred method - I know I couldn't do without my OPKs because I can't seem to work out Maybe Baby at all. :D

[luckymama]

when do you use your maybe baby, mornings?
i have a donna saliva monitor which has a slighter higher magnification than the maybe baby, and i use it in the morning.
i put my tounge to the roof of my mouth and kinda let the saliva pool there, and then i use my finger to scoop up some saliva and let a drop fall onto the slide, then i leave that part on the desk till i can see that its dry, and voila.......give that a go and see if it works.
i havent really used OPKS that much, i was always worried id miss the surge.

[MrsMiggins]

What an interesting read!!

I have found since I started charting (about a year and a half before falling PG with DD), that I find it soooooo.... much easier to know what's happening with my cycles. Some cycles the O date is undeterminable (more often than not I think, due to the fact that the temps may have been taken inaccurately), but all in all, I have found it to be the only way I know what is happening with my irregular cycles. Otherwise I'd have no idea when to test or when to expect my period. Plus, the Fertility Awareness Method is not an option for me as I produce very little fertile CM.

I don't think charting BBT is great for predicting ovulation (unless you have cycles like clockwork), but it can help you keep track of where you're at, understand your menstrual cycle better & often see when you did O (after the fact) and make an assumption of whether a cycle could result in a successful PG.

[chicken]

This is only my first month of using Maybe Baby. I was using it the mornings only, but when I read that some women use it in the evenings, I started doing that as well. I was getting confused because this week I've been getting partial ferning at night, but then just pebbles in the mornings. But I think I may have found the problem. I was getting up and going straight to the bathroom to do my Maybe Baby with my manky morning mouth and I think this may have been affecting the results. This morning I did it straight away and got pebbles again. But I also did it about half an hour later (had a shower, etc), and then got ferning. So maybe I am ferning after all (it would fit with when I think I should O which is on Thurs).:smiliedance:

How long after getting up to you use your saliva test?

If you use OPKs at the same time each day, then you shouldn't miss your surge. An OPK should always be positive for two days (the day before O and O day). But I liked the idea of the saliva test because it gives an even earlier warning (if I can figure out how to read it properly!).

[luckymama]

I don't think charting BBT is great for predicting ovulation (unless you have cycles like clockwork), but it can help you keep track of where you're at, understand your menstrual cycle better & often see when you did O (after the fact) and make an assumption of whether a cycle could result in a successful PG.

i totally agree with that, but i am so certain i od, but from my chart you wouldnt think so, so i just wanted to feel better by finding research that shows that it doesnt work for everyone IYKWIM :rolleyes:

[chicken]

Doula - i just read your post again. Did you say you actually let your saliva drop onto the slide? I'm not using that much saliva at all - only a smear. Maybe I'm not using enough? But they say only to wait 10 minutes - does your drop dry that fast?

[luckymama]

i only put a really tiny drop on there, and i do it after dropping my DF at the train station, but i dont eat or drink or anything, so by the time i do it, i have swallowed away all the manky stuff in my mouth, and the saliva drop is clear (rather than whiteish)

[MrsMiggins]

i totally agree with that, but i am so certain i od, but from my chart you wouldnt think so, so i just wanted to feel better by finding research that shows that it doesnt work for everyone IYKWIM :rolleyes:

Yep! IKWYM! I often found too that after a few more temps & more data, FF could sometimes change your O date anyway. Just stick it out, maybe you'll still get a coverline for this chart (I just had a quick squiz at it!) Your cycles seem to be very similar to mine.

I also had cycles where I felt sure I'd O'd, but FF didn't give me a coverline. Could be their software too. Have you tried changing the detection method? Wait a few more days, have a few more temps & other data, then try changing the detection method & see what you get.


:fingerscrossed:

[luckymama]

yup ill give that a go, but seriously id wager almost anything on the fact that i od on sun, would even go with monday, but no later than that, since all my fertile signs have gone pretty much :rolleyes:

[MrsMiggins]

Yeah, looks like it. Sometimes the software will only recognise O on say for instance, day 14 when you've got several temps after cd14. It's just how it detects it. I've had it change O dates for me on cd12-14 when I'm entering temps in cd29+.

[luckymama]

i spose i really shouldnt have spent money paying to keep the VIP feature, its prob a waste of money, i should have just did it on paper or something, oh well :rolleyes:
i am seriously tempted not to take temp anymore..............it would be great not to have to wake up and take temp at 6am every morning...hmm lets see how long i stick to not temping huh :laughing:

[MrsMiggins]

Really? I was glad I upgraded - it meant I could go on charting after I had DD, which was helpful even though we weren't trying to conceive again straight away (well, obviously we were trying a little bit :laughing: )

I just haven't the first clue what's going on with my cycles unless I chart BBT. Although I'm the first to admit I got very slack at temping after I had DD.

I tried working it out on paper, but the whole coverline thing just had me bewildered! Much easier having some up to the minute hi-tech software doing it for you! ;)