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How to Chart Your Basal Body Temperature and Detect Ovulation

By Rachel Gurevich, About.com

Updated May 28, 2008

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

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How to Take and Chart Your Basal Body Temperature

Now that you have a BBT chart picked out, you’ll now need to get a thermometer. There are tons of specially made basal body thermometers for sale. While some come with interesting features, the honest truth is that any good, regular thermometer will work.

Taking your Basal Body Temperature

Taking your basal body temperature isn’t too hard. There are a few must-keep rules:
  • You need to take it at the same time (plus or minus no more than 30 minutes) every morning. (If you take it at 7:30 a.m., for example, you don’t want to take it earlier than 7 a.m. or later than 8 a.m. on other days.)

  • You can not get up, sit up, walk around, or go to the bathroom before taking your temperature. The minute after you wake up, you need to pop the thermometer in (which you hopefully placed within hand’s reach the night before.)

  • You need to have had at least three to four straight hours of sleep before taking the temperature in the morning. If you stayed up all night, or you woke up and walked around at night repeatedly, it will throw off your results.

  • You should use the same thermometer throughout the cycle. (If you buy a new one, start using it on day one of the next cycle.)

If you want more details on taking your BBT temperature, read this article on how to take your basal body temperature.

When to Start Charting Your Cycle

Ideally, you should start charting on the first day of your period, and continue to take your BBT temperature every morning throughout the entire cycle. Every day, mark your waking basal body temperature, along with the time that you took your temperature.

After you have experience with charting, you may discover that you can skip the first few days of your period and start taking your temperature around day 5 or 7. Until you know when you tend to ovulate, though, it’s best to take your temperature all the way through the cycle.

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