Even if they do have pain while undergoing medical procedures, some premature babies may not show any obvious signs of discomfort, according to a study by researchers at University College London, U.K.
The scientists observed the brain activity of 12 babies while they had heel prick tests. Most of the babies displayed both brain and physical responses. However, some of the babies had a brain response to the pain but no obvious physical response, BBC News reported.
"Although the study is small, it does raise concerns about the tools normally used by doctors to establish whether a baby is feeling pain," lead researcher Dr. Rebeccah Slater said in a prepared statement. "Infants may appear to be pain free, but may, according to brain activity measurements, still be experiencing pain."
The study appears in the journal Public Library of Science.
There's debate about premature babies' ability to feel pain and how much painkiller is needed to make them comfortable, BBC News reported.