How do you take your basal body temperature ?

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We thought it would be worth covering this subject as we have had a few customer service queries recently concerning basal thermometers and how they should be used.

Here are our tips to using basal temperature to monitor fertility:

  • The basal temperature increases and stay elevated once ovulation occurs.
  • Use a high accuracy digital thermometer that has two decimal places
  • A fahrenheit thermometer is best if you can get one
  • We have found that the mouth, under the tongue, is the most reliable place to take the temperature.
  • Take the temperature first thing in the morning before rising from your bed.
  • Do not drink anything before you take the temperature
  • Place the thermometer under the tongue and leave it there keeping your tongue firmly pressed on it and still until it bleeps indicating it has reached a steady temperature. This make take several minutes.
  • Take the temperature at the same time each day. It may be worth setting your alarm.
  • Basal temperature means your resting temperature so it must be the first thing you do as soon as you wake up.
  • Keep a record of your basal temperature on a chart each day
  • After the first month you will start to see a pattern which should help you to know when your fertile time is.

Visit Access Diagnostics UK fertility site for fertility thermometers, ovulation tests, early detection pregnancy tests, home fertility tests  and fertility friendly lubricants.



Using a digital thermometers for basal temperature monitoring fertility

BBT Digital Thermometer Fertility 


How do you use a digital thermometer to predict your fertile time ?


Your basal body temperature is your resting body temperature on waking 1st thing in the morning ie before you get up or move about

By measuring your basal temperature every morning you can pinpoint & later predict ovulation.

Measuring basal body temperature or BBT can be a way for women to pinpoint their fertile time. This is beacause the basal temperature increases by between 0.5 and 1 degree fahrenheit (a quarter  to a half degree centigrade) at ovulation. The temperature then remains elevated until just before menstruation commences.

Interestingly if a pregnancy occurs the BBT remains elevated for approx the first 3 months, so this can be an early sign of pregnancy.

The temperature should be taken immediately upon waking and recorded on a chart (a BBT chart is ideal)

If this is done over several months a characteristic pattern emerges that allows a woman to predict as well as pinpoint ovulation.

Click here to buy digital themometers suitable for basal body temperature (BBT) monitoring

Basal Body Temperature Charting

What is my BBT ?

Your basal body temperature (BBT for short ) is your resting body temperature ie your temperature when you are at rest.

When is the best time to measure my BBT ?

For most women the best time to measure the BBT is first thing in the morning when you wake, before you get out of bed, and before you do anything at all.

How do I measure my BBT ?

You will need to use a high accuracy clinical thermometer- the easiest to use is a digital thermometer that measures to 2 decimal places

Where do I put the thermometer to measure my BBT ?

For most women the best & simplest place to measure your BBT is under your tongue

How long do I leave the digital thermometer under my tongue ?

Most digital thermometers will beep when they have reached a stable temperature, making it quick and easy to know when to remove the thermometer. It usually takes around 1-2 minutes for this to happen.

What do I do with the basal body temperature results ?

You will need to chart the BBT results on a temperature chart , so that you will be able to see the pattern develop.

Here is an example of a BBT chart

Is there anything I should not do when doing my BBT ?

Moving around, eating, drinking, smoking & even talking will raise your temperature, so make sure you do the temperature immediately upon waking each morning. If possible measure it while you are still “half asleep”.

What else can raise my basal temperature apart from ovulation ?

Illness if associated with fever will alter your resting temperature making interpretation of results problematic.

How does BBT charting help me predict my fertile time ?

Charting your basal temperature is helpful in determining whether and when ovulation occurs. Ovulation is the release of an egg (ovum) from the ovary and usually happens only once in each menstrual cycle. Conception can take place only if intercourse takes place immedictaely before , during or immediately after you ovulate.

By carefully recording your basal temperature when you first awaken, you will begin to notice a pattern of temperature fluctuation in your monthly cycle. The slight increase in basal temperature is an indication of ovulation or fertility.

Do I need a special thermoeter for BBT charting ?

You may use any clinical thermometer, as long as it is high accuracy. As the temperature change you are looking for is very small, it is best to use a thermometer that shows very small fluctuations in temperature.

Many women find it simpler to use a high accuracy digital thermometer rather than a glass thermometer, as they are quick and simple to interpret, and they beep when they reach a steady temperature. Glass thermometers can also be fragile.

Click here to find out more about high accuracy digital thermometers suitable for BBT or to buy one

Click here to visit babycentre who have free BBT charts that you can download and print

Other Signs Of Ovulation-Basal Body Temperature Rises-BBT

How to take your Basal Body Temperature (BBT)

1. Taking Your BBT Temperature

Your Basal Body Temperature is probably best taken orally (simplest in my opinion ), by placing the thermometer under your tongue. BBT temperature refers to a ‘resting’ or ‘base’ temperature. That means that your BBT must be measured before activity, after at least four hours of sleep. Take your BBT temperature first thing each morning (ideally at the same time each morning) – as soon as you wake up and before you get out of bed or have a cup of tea! Other things such as hot drinks, infections, illness etc can affect your BBT reading.

2. Charting Your BBT Temperature
Starting on day one of your menstrual cycle – the first day of your period – begin recording your BBT temperature using graph paper. Each morning, record your temperature. Plot each day’s BBT on the a graph. Your temperature rise may be sudden, gradual, or in steps. The pattern may vary from cycle to cycle.

3. Predicting Ovulation
Typically a rise of at least 0.4 to 0.6 degrees centigrade or  will take place at ovulation, though for different women the temperature increases may be sudden or gradual. Over time, charting you BBT will help you predict ovulation.

It is important to remember that the rise in your BBT (basal body temperature) does not tell you when you are most fertile or about to ovulate. It tells you when you already have ovulated. Women are most fertile in the few days before their peak temperature.

Click here to see Digital Thermometers suitable for BBT