Ideally, you should start charting on the first day of your period and continue to take your BBT every morning throughout the entire cycle. For the most accurate record it’s recommended that you take your temperature at the same time each day. Your temperature should be taken before getting out of bed, or even sitting up in bed, preferably with 5 hours consistent rest but at least 3 hours, without speaking or drinking anything beforehand. You can also record other indicators and possible influences such as when you have sex, your cervical secretions, stressful days or headaches etc. These can all help you determine when you ovulate and but also provide possible reasons for affecting changes in your BBT.

You need a BBT digital thermometer to measure for basal body temperature. A BBT thermometer shows two decimal places for increased accuracy. They are usually available to buy either at the chemist or online. There are many apps on the market that help you record, monitor and interpret your results. It’s a good idea to do some research into the various apps available, alternatively you can find offers for a free fertility calendar, where you can track your BBT, periods, and other ovulation symptoms.

There are a few things besides ovulation that can affect your BBT, so it’s good to be aware of them. It’s important to understand that fertility isn’t the only thing that may influence your BBT. Not getting enough sleep, interrupted sleep or sleeping more or less than you usually do can have an impact on your resting body temperature. Consuming more than a couple of units of alcohol can also lead to an elevated body temperature. Being unwell can cause a high temperature which affects the body’s resting temperature. Stress, shift work, certain medications and some gynaecological conditions can also have an impact on your BBT.