Ovulation Prediction Methods.

Basal Body Temperature Method (BBT)

The most traditional method used to detect whether a woman is ovulating is based upon measuring her basal body temperature (BBT) using a clinical thermometer. This is still the typical first line test that a GP may use to assess whether or not a woman is ovulating each month. The method is also used as part of natural family planning methods and thermometers and charts are available in many pharmacies.

It has been known for many years that the temperature of a woman's body at rest (BBT) rises very slightly after ovulation has occurred. This small increase in temperature is caused by rising levels of the hormone progesterone which is released after ovulation has occurred.

In order to detect this rise in temperature a woman must take her temperature as soon as she wakes each morning and before she gets out of bed. In addition the woman must not eat or drink before she takes her temperature otherwise false temperature readings may occur. As soon as a small rise of temperature is spotted - the rise is usually around 0.2-0.4C - the woman can assume that ovulation has just taken place, or at least has taken place within the last few days.

This method is useful to confirm that a woman is ovulating each month and by recording her temperature on a chart over several months she can begin to predict when the most fertile days of her cycle are going to be, which is of course necessary for couples either trying to obtain, or trying to avoid, pregnancy.

We recommend that you use the Bioself fertility indicator for accurate recording of your basal body temperature but if you do want to use charts you can download copies here - Fahrenheit chart of Celsius chart

The biggest concern with this method is that the temperature rise occurs after ovulation has occurred. This means that it has little practical value for women wishing to become pregnant now. In the past doctors have told couples to have intercourse when the temperature rise is seen in order to achieve pregnancy but recent research in the USA suggests that this is too late.

If a woman has regular cycles she could use this method to help detect the period of the month that she usually ovulates. In this way she could guess the best time to have intercourse to have the greatest chance of becoming pregnant. However, the BBT method is simply not very easy to use or convenient. It relies on detecting small differences in BBT and this can be unreliable in practice because it is hard for a woman to comply with the testing regime. In addition the results can be influenced by numerous factors including eating spicy food, drinking alcohol, lack of sleep or having a cold. All these things make this method difficult to use and in practice even experienced doctors can find the charts difficult to interpret.

Our Bioself Fertility Indicator uses your body temperature and your cycle length to predict when you will be most fertile.

However, the Bioself fertility indicator uses the BBT and calendar methods with modern technology - microprocessor and thermocouples - to make a highly effective and simple to use device. The device prevents a woman from taking her temperature at the wrong time of day, or removing the thermometer before the temperature has been accurately record. It also acts as an alarm clock each day to remind her to take the temperature and furthermore it prevents the possibility of transcription error since the women does not have to record the temperature on a chart. Consequently this device seems able to give results which are close to the reliability of controlled BBT studies. Recent clinical trials have shown this to be a very effective aid to conception and also in natural family planning - Click Here for more details on the use of the Bioself Fertility Indicator.

Viscosity of Vaginal Fluids

This method involves checking the mucus secreted by your vagina every day. Some women may be aware of this method if they have previously been interested in natural family planning.

For most of the cycle, the mucus will be absent or white, quite thick and sticky. As you get nearer to the time of ovulation, levels of the hormone oestrogen rise, stimulating the cells at the cervix to produce more mucus. Just before ovulation the mucus changes character and becomes a clear, watery, elastic texture like raw egg white, feeling wet and slippery, which means that it is receptive to sperm at this time - you may be able to stretch the mucus between your thumb and forefinger without it breaking. Immediately after ovulation, the mucus becomes thick and cloudy again. This method is also difficult to use as changes in mucus can also be caused by infections and certain medicines and can be masked by intercourse.