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Your Basal Temperature

If you want to boost your chances of getting pregnant, you need to find out when you ovulate. Ovulation is the time when your ovaries release an egg that can be fertilised by sperm, leading to pregnancy, but that egg is only viable for a maximum of twenty-four hours. You need to make sure sperm can reach it within that time period to give yourself the best possible chance of getting pregnant. The time when sperm can survive long enough in the body to reach that egg is known is the fertile window and it is six days long. Sperm can survive for five days, so intercourse in that five days running up to ovulation can result in pregnancy, as with the day after, while the egg is still viable, for a total of six days.

One of the more reliable ways to identify ovulation is to measure your basal body temperature. Doing this effectively and interpreting it to learn about your fertility means learning just what your basal temperature is, and that’s what Ovusense is taking a look at today.

Temperature and Metabolism

Your temperature is largely driven by your metabolism: the process by which your body converts energy into food. This creates heat as a by-product of the process: the harder your body works, the hotter it gets.

This means to get a ‘true’ temperature for your body, you need to measure when your metabolism is at its slowest. This happens when you’ve been at rest for a long period, for example during a long night of sleep. Because you’re not active, you’re burning the smallest possible amount of energy, and so your temperature is at its lowest sustainable level. This is your ‘basal’ body temperature.

Why is it Important?

This minimum temperature for your body responds to different bodily processes. If you can measure it accurately, you can tell what’s going on in your body as your temperature changes! Specifically for your fertility, your basal body temperature rises by a tenth of a degree as you ovulate – and for many women this is preceded by a drop of one tenth of a degree for the three days before ovulation, giving you more advance warning.


Tracking your basal body temperature is a very manual process – it’s a lot of work, and there are lots of opportunities for it to go wrong. Even if it all works perfectly, it still gives you access to no more than three fertile days out of six.

OvuSense offers a more reliable solution. We track your core temperature, which our algorithm can map to your progesterone levels: a direct indication of how your body is preparing for ovulation. Even if you have irregular cycles or a condition like Polycystic Ovary Syndrome, OvuSense can start providing you with predictions of when you will ovulate with only a few days of data, so you can start planning for pregnancy right away!