The different types of BBT patterns
If you’re charting your basal body temperature (BBT) you’re probably familiar with these three patterns:
Monophasic (one-phase) charts show no shift in temperature comparing before and after ovulation. Monophasic charts often occur during cycles where you don’t ovulate (anovulatory cycles).
Biphasic (two phases) pattern charts are your typical ovulatory charts. The temperature readings fluctuate a bit, but in general, they are low before ovulation, and high after.
Triphasic (three phases) pattern charts are similar to biphasic charts but instead of 2 phases, there are 3! The temperature before ovulation (low), after ovulation (high), and after implantation of the embryo (even higher). Let me show you an example. Do you see where that arrow is? That third shift in temperatures? That’s your triphasic pattern.
Triphasic Patterns and Hormones
There is a feedback loop of hCG (the pregnancy hormone that is secreted after the embryo has implanted) and the hormone progesterone, which causes your temperature to rise.
These hormones cause changes in temperature that are helpful when charting, but a third jump in temperature, which is when the embryo implants, is surprisingly difficult to see on a chart! Analysis of close to 150,000 charts of Fertility Friend (“Triphasic Pattern and Pregnancy”.), showed that a triphasic chart was found only in 12.5% of charts. On average, this temp rise happens 9 days after ovulation, around the average day of implantation!
Not Just When You’re Pregnant
So 12.5% of pregnancy charts showed a triphasic chart, but that doesn’t actually tell us if it’s related to pregnancy if we don’t know how many charts of NON-pregnant women also showed a triphasic pattern. Well, it turns out that of the regular cycles, cycles where you don’t end up pregnant, only 4.5% of cycles show a triphasic pattern. Quite a big difference!
But can we conclude that a triphasic pattern means you’re pregnant?: No, even though the prevalence of a triphasic pattern was higher in pregnancy cycles, they still occurred among those who DID NOT get pregnant.
Most importantly, NOT seeing a triphasic pattern doesn’t mean you’re not pregnant either, as the vast majority of women who did conceive had a plain ol’ biphasic pattern!