Q: How do I take a rectal temperature?
A: To take a rectal temp, first dab petroleum jelly on the bulb of the thermometer. Place your baby belly-down on your lap or on a bed or changing table, then gently insert the bulb 1/2 to 1 inch into your child's rectum. Loosely hold the thermometer in place with two fingers until it beeps. To get an accurate reading using an oral thermometer, wait at least 15 minutes after your child has had anything hot or cold to eat or drink before you take his temperature. For babies, a digital rectal thermometer provides the most accurate reading; you can switch to an oral one when your child turns 3. --Avery Hurt
Originally published in Parents magazine, October 2007. Updated 2009