OvuSense logo

What is Basal Body Temperature?

Preparing to get pregnant means much more than painting a nursery and picking out a pram. As you try to conceive, you’ll be learning a lot about the science behind the process – especially if you have any challenges affecting your fertility that you need to work with.

One of the scientific terms you’re going to encounter is Basal Body Temperature. It’s not immediately clear what it means or why it’s important but understanding it could be the most vital step you take towards getting pregnant. Luckily OvuSense is on hand to explain.

What Does It Mean?

The word basal is the confusing bit of this term: it’s easy to understand what your body temperature is, but putting basal at the front complicates the issue. In biology, basal means the basic or minimal level required to maintain normal functioning. A basal diet is the bare minimum of calories and nutrients needed to keep your body ticking over.

Your basal body temperature, therefore, is your minimum body temperature: the one you reset to when you’re at rest, with no physical activity stressing your system. It’s the temperature your body sinks into when you’re asleep, and all your processes slow down.

Why is it Important?

Measuring your BBT tells you a lot about your fertility. Looking at the temperature of the body when it’s totally at rest allows you to see the patterns in it that tell you when key events like ovulation are happening. Taking away interference from physical activity, and differing ambient temperatures exposes those patterns so you can track them and interpret them.

What Does it Show?

The most important thing for you is that your BBT is a good predictor for ovulation. Your BBT frequently drops by a small but measurable amount immediately before you ovulate, then rises by an average of 0.2 degrees for the next 72 hours. Identifying this pattern lets you know when you’re ovulating and that’s the best time to try and conceive!


There’s one major challenge to measuring your BBT: taking your temperature before you engage in any physical activity does require you to take some physical activity. That means any manual measurement is going to be thrown off by a small but important amount.

OvuSense doesn’t suffer from this problem. Our sensor measures the temperature in your vagina across the whole night, presenting you with results in the morning. Processing that data with our app lets us alert you when you’re due to ovulate with 24 hours notice and is correct 96% of the time, which could be that vital edge you need to conceive when you want to!

Find out more about core temperature technology and fertility here