How to Measure a Temperature Taking a Child's Temperature Obtaining an accurate measurement of your child's temperature requires some practice. If you have questions about this procedure, ask a physician or nurse to show you how it's done. Then ask them to watch you do it. Where to Take the Temperature Temperatures measured rectally are the most accurate. Temperatures measured orally, by electronic pacifier, or by ear canal are also accurate if done properly.
Temperatures measured in the armpit are the least accurate, but they are better than no measurement.
The reason you need to take a rectal temperature for young infants is that if they have a true fever, they need to be evaluated immediately. Have your child lie stomach down on your lap. Before you insert the thermometer, put some petroleum jelly on the end of the thermometer and on the opening of the anus. Insert the thermometer gently into the rectum about 1 inch. Never try to force it past any resistance.