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BBT charting stands for body basal temperature, which is your base temperature first thing in the morning on rising.

Charting can show you when you’re ovulating, how well & if you’re producing enough Progesterone after ovulation to keep your temperature high for a good period of time. If you're trying to get pregnant we really need it to stay high enough for for implantation to occur & pregnancy to hold. It’s a great tool & in my opinion by far outweighs ovulation strips.

The other reason I like BBT charting is that the only other ways to confirm someone is ovulating is either through an ultrasound or a day 21 progesterone test, both of which are not realistic to be doing monthly. The day 21 progesterone test also only works if you’ve ovulated on day 14, otherwise it’s going to give you a false reading & chances are if you’re doing one in the first place it’s because you’re unsure when you’re ovulating, so how does that one work?!


The trouble with ovulation strips, especially for people with PCOS, is that it’s measuring the LH surge which happens before you ovulate. However with PCOS, you can have many surges as your body is trying to ovulate without success. So you may think you've ovulated when you haven't.

The App I get my patients to use is the Fertility Friend App. I find it the easiest to use & the graph the clearest to understand.


In the first part of your cycle, or follicular phase, your temperature should be around 36 to 36.5 degrees. This is when your FSH and Estrogen are dominating your cycle. Once you ovulate you start producing Progesterone. It's the Progesterone that elevates your temperature 0.3 to 0.5 degrees. By charting we should be able to see a distinct shift in temperature between the follicular phase and the luteal phase. If your temperature isn’t biphasic and doesn’t change then this tells us that ovulation hasn’t occurred. A woman may still get a bleed with this kind of chart but it is what we call an anovulatory bleed.

On the other hand if there is a rise in temperature indicating, ovulation but the temperature starts dropping earlier than day 10, it can indicate luteal phase insufficiency.


To chart, take your temperature using a digital thermometer underneath the tongue, as soon as you wake up. You need t have had 3 to 4 hours of sleep prior, & test roughly the same time every day. Charting can't predict when you're going to ovulate, it can only tell us once you have. This is because we are relying on the temperature to go up & stay up for at least 3 days to tell us ovulation has occurred.

A couple of months charting will give you a more accurate idea of when you're ovulating.

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