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BBT Trend


Temperature Trend

The Pregnancy Monitor displays, when relevant, an indicator of your temperature trend. It also displays basic stats of occurrence.

Knowing if your BBT is on the up, down or stable trend is an additional clue about what may be going on with your cycle.


The purpose of the tool is not to replace what you can see on your chart with your own eyes. The BBT trend tool provides an objective trend measure that can be used for comparison and statistics.

The BBT trend takes into account several temperature points at the same time. It is based on an imaginary average line, thus ignoring the usual BBT jitters.


The BBT Trend tool also displays the frequency of occurrence of your trend on pregnancy charts as observed on Fertility Friend at your current DPO.

Remember that this is not a measure of your chances of pregnancy but just one factor among many others. That said, it is interesting as it shows you whether your pattern is common or not among pregnancy charts.

Why does it matter?

During a normal cycle the corpus luteum (the "shell" that contained the ovum) controls the production of the hormone progesterone. The progesterone controls your BBT (it raises it).

At the end of your cycle, as the corpus luteum starts degrading, the progesterone production tapers which in some cases can be seen by a slow downwards trend on the BBT

In case of pregnancy, as the corpus luteum starts degrading, the embryo implants and takes over hormone production and maintains the BBT at a high level.

Note, however, that like any other sign, this is not accurate or observable all the time. It is just an additional piece of the puzzle.

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