Bear in mind that an external armpit reading can be as much as 2 degrees lower than an internal rectal reading. (babycenter.com)
An armpit reading, which is external, can be as much as 2 degrees lower than an internal rectal reading. (babycenter.com)
And if it involves a fever, those hourly readings can be exhausting if you have to wash off a thermometer or do a rectal reading. (pregnancymagazine.com)