Ovulation and temperature

One of these changes is your basal body temperature – or BBT. Tracking changes in your BBT can be a really helpful indicator of when you may be ovulating. All you need to do is get a good quality BBT thermometer from the chemist, and start keeping a record in your daily fertility diary.

 

When trying to conceive it's important to keep a daily fertility diary to note your body’s changes, and keep a track of your menstrual cycle. 
 

We don’t notice the variations in our monthly BBT because they are so slight, which is why it’s essential to get a good quality thermometer and take your temperature at the same time every day. You need to take your temperature every morning, before you get out of bed, and after you've had at least three hours of uninterrupted sleep. Note the time on your diary, as well as the temperature.
 

Most women don’t need to take their temperature vaginally, orally is fine. If you aren’t seeing any clear pattern in your BBT after tracking it for a month, you may need to start taking your BBT vaginally. Don’t do this until you start a new cycle though, for accuracy. To take your temperature vaginally, simply insert the tip of the thermometer inside your vagina in the morning and record your temperature as usual. Some women who sleep with their mouths open choose to take their temperature vaginally because of this. Note: for oral BBT it’s best to buy a digital thermometer. For vaginal tracking of BBT buy a mercury thermometer.

 

The obvious drawbacks to measuring your fertility from your BBT are of course, if you have interruptions to your sleep, you’re travelling, you may be sick (our temperature is another key indicator of flu or infection), or a different waking time. Alcohol, electric blankets, and even going to the toilet before taking our temperature can affect the reading, which is why it’s important to keep it beside your bed and not get up before you take your BBT. Our temperature also fluctuates during the day, which is why it’s imperative that you take your temperature at the exact same time every day. If you do have to get up at a different time due to work or other commitments, make sure you have at least had three hours of uninterrupted sleep.

 

If you keep the same temperature every day, then at, say, day 17, there is a temperature increase of 0.5 to 1.6 degrees Celsius; it’s a fairly clear indication that you've ovulated. Why? Releasing an egg stimulates the production of the hormone progesterone, which raises body temperature. 
 

Similarly, if by day 28 your BBT decreases by between 0.2 – 0.5 degrees, your period is about to arrive and you’re not pregnant.
 

You're most fertile in the two or three days before your temperature rises, so charting your temperature for a few months will help you detect a pattern and pinpoint your likely ovulation date. Then you can make sure you have sex in the two days before you ovulate, to increase your likelihood of conception success. 

 

A small number of women find it impossible to notice patterns in their temperature, due to lifestyle factors. In this case, try some of the other suggestions to track your fertility cycles, such as cervical mucous, the state of your cervix or noting your monthly cycle.