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Basal Body Temperature and Ovulation

When you’re trying to conceive, you need a plan: this is especially true if you have any kind of condition that might interfere with your ability to get pregnant. If you have PCOS (Polycystic Ovary Syndrome) that causes you to skip ovulating altogether, naturally irregular cycles or are suffering from high levels of stress, you need to identify when you ovulate and focus your attempts at getting pregnant on that key moment in your cycle.

There are lots of different ways you can try to predict your cycle and learn ahead of time when you’re going to ovulate: online calculators are non-invasive but don’t gel well with an irregular cycle. Ovulation Predictor Kits (OPKs) are as convenient as pregnancy tests, but can find it difficult to make accurate predictions if you have anything throwing off your hormone makeup, be it stress or medication.

False positives and negatives are no use to someone trying to make a plan that maximises their fertility and helps them get pregnant when they want to.

One of the more accurate things you can measure to determine when you’re due to ovulate is your basal body temperature (your ‘BBT’). This is the minimal temperature your body falls to in sleep, when it’s not raised and distorted by activity of any kind. Measuring this basal temperature shows fluctuations that can reveal when you’re ovulating.

The pattern you’re looking for is a small drop followed by a steady, 72 hour raised average. A significant majority of people experience a drop in body temperature the day before ovulation, and even more see a raise of .2 degrees centigrade for the three days following.

The advantage of this method is that it doesn’t depend on matching you to an average body’s behaviour, like hormone testing kits – the key is spotting the pattern for your body. Even if your temperature tends to be a little higher or lower than average, you can still spot when it changes.

It takes some work to spot these patterns: you need to take your temperature first thing in the morning every day to establish a baseline average, and then for longer to identify those changes. If you move around too much before you take a reading, you won’t get an accurate result. Most oral thermometers are also only accurate to the nearest 0.1 degree celsius, which can often miss subtle changes in temperature and also impact the accuracy of the results. You also need to be vigilant with your record keeping to plot all those daily results, and spot the trends that reveal your fertility.

OvuSense has a solution for these problems: our vaginal sensor measures the true fluctuations of progesterone throughout your cycle, giving a truly accurate reading, and produces a prediction that can notify you when you’re due to ovulate with 24 hours of notice that is clinically proven to be correct 96% of the time!

Find out more about core temperature technology and fertility here