Low body temperature: Cause for concern?

Dear Alice,

I have a question regarding basal body temperature. My husband and I recently began the fertility awareness method, and my basal body temperature is extremely low. For the last 20-some days it has been off the chart low (below 97). I just went off the pill, and I am taking no other medications. Is this normal? I also haven't ovulated yet, which doesn't concern me. I'm sure it could take a couple months to get regulated again. But I don't understand the low temperature. Thank you for responding.

— Ellie

Dear Ellie,

Deviating from the norm can be a bit troubling; however, a lower than "normal" body temperature may not be something to worry about. Although 98.6 degrees is the commonly accepted average in the population, individuals fluctuate from the average. In your case, having some (or all) days below 97 is not unusual, and is not considered unsafe unless your body temperature is below 95 degrees. As an aside, you're right that it may take several weeks to months before you ovulate after going off birth control, this is normal.

The basal body temperature method you mention, that some people use to chart fertility, requires measuring your temperature at rest each day. Before ovulation, a temperature between 96 and 98 degrees is normal. Your body's at rest temperature should rise slightly, to between 97 and 99 degrees, beginning on the day of ovulation until the start of your period. Changes in temperature may be extremely small — maybe only 1/10th of a degree. In order to get an accurate reading be sure to take your temperature at the same time each day — try making it a part of your daily routine before you get out of bed. Consider using a rectal reading if you aren't already, which tend to be more accurate than oral readings.

In addition to the basal body temperature method, you could try the calendar method, which involves charting your menstrual period each month, or the cervical mucus method. The mucus method (also known as ovulation or Billings method) requires that you keep track of mucus discharge consistency during your cycle since the most mucus appears immediately before ovulation.

Keep in mind that body temperature may fluctuate for a number of reasons. It's usually lower in the morning, or at rest and, as expected, may drop after being exposed to cold. While hovering around 96 or 97 degrees is normal for some, the following conditions could also contribute to a suddenly or persistently low body temperature:

  • Hypothyroidism
  • Diabetes
  • Liver or kidney failure
  • Infection
  • Endocrine dysfunction
  • Side effect of certain medications
  • Excessive alcohol or drug use

If you have any of these conditions, or your low body temperature is a concern for you, see a health care professional. They can rule out any underlying conditions and help you find a fertility method that works for you and your partner.

Remember, what's normal for others may not be normal for you — everyone is different!

Last updated Apr 10, 2015
Originally published Jan 09, 2009

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