OvuSense logo

How to Detect Ovulation Using BBT

If you’re trying to get pregnant then the most important thing you need to know is when you ovulate. If you have a very stable, regular cycle, then you can often know, reliably, when you’re due to ovulate next and therefore when you stand the best chance of getting pregnant. If your cycle is less regular or you have a condition that can affect ovulation, delaying it or even causing your body to skip it altogether, then it’s all the more important for you to identify those rarer times when you do ovulate. Ovulation is your body’s one chance each month to conceive, and if yours misses this step then you have fewer chances to get pregnant. Each remaining one is more precious and important.

One of the ways of detecting ovulation is using your BBT: your basal body temperature. It’s accurate, and it’s not affected by hormone disruption. Conditions like Polycystic Ovary Syndrome and Hyperthyroidism can delay or prevent your body ovulating because they’re driven by disruptions to the hormones that regulate your cycle. Unfortunately, the most convenient and widespread ways of detecting ovulation also rely on those same hormones. This means that when you really need an Ovulation Predictor Kit to help you get pregnant, most of the ones on the high street won’t work for you.

BBT (or Basal Body Temperature, to give it its full name) is not distorted in the same way. Your basal temperature could be more comprehensibly called your ‘base’ temperature – that low, basic level your body’s core temperature falls to during a long rest. When you sleep your metabolism, and even your heartbeat slow, and your temperature drops. At this base level, small changes indicate what your body’s menstrual cycle is doing, so accessing this information can help you detect ovulation.

This method requires you to take your core temperature every day, as soon as you wake up, before your metabolism starts to warm your body. Most BBT monitors use oral thermometers which, whilst being easy to use, are not as accurate as other methods as they only provide temperatures to the nearest tenth of a degree. This can result in subtle temperature changes going undetected and can have an impact on the accuracy of your ovulation prediction.

You then need to record that information – whether you simply write it down, or plot it onto a graph to help you spot patterns, you need to keep a record. Spotting a dip, followed by a sudden but sustained rise over your average is a good indicator that you’re ovulating. This method of using data from previous month's cycles can be insufficient however, for those with irregular cycles or fertility issues, such as Polycystic Ovary Syndrome (PCOS).


In order to address the above issues with BBT monitoring, OvuSense have created an all-encompassing method of predicting ovulation, using a vaginal sensor and an accompanying app. The sensor is inserted overnight in order to give the truest possible reading of the fluctuations in your progesterone, which is sent automatically to the app that then uses an algorithm to turn that data into a personalised prediction of your ovulation date 24 hours in advance! The prediction is clinically proven to be correct 96% of the time and gives you the best chance of getting pregnant.

Find out more about core temperature technology and fertility here