Find a comfortable and private location. Remove your pants or undergarments for ease of access.
Stand with one foot elevated. For example, if you are in the bathroom, put one foot up on your toilet or the edge of your bathtub. This puts you in a position that allows the thermometer to slide in easily.
Aim the bulbous tip of the rectal thermometer at an angle toward the small of your back as you insert it slowly into your rectum, allowing 1/2 inch of the thermometer to enter.
Wait one minute and then remove the thermometer to read the temperature.
Lay your baby comfortably on her back on a changing table, bed or other suitable surface.
Insert the bulbous end of the thermometer into the opening of the baby's rectum. Slide it in 1/4 to 1/2 inch.
Hold the thermometer in place for a minute before removing from the baby's rectum to read the temperature.