In a study whose highlights indicate a need to review pain relief procedures for babies, Oxford University researchers concluded that they are just as sensitive -- possibly more so -- than adults.
Babies' brains exhibit the same patterns as those of adults upon experiencing physical pain, according to the pioneering study in which functional magnetic resonance imaging (fMRI) technology was used.
Working with 10 healthy infants of between one and six days old and 10 healthy adults aged between 23 and 36 years, the research team poked the bottom of their feet with a retracting rod.
Babies were accompanied by their parents and study authors say the sensation created by the retracting rod was like being poked with a pencil and did not wake the babies who had fallen asleep in the MRI scanner.
Comparison of the babies' scans against those of the adults found that 18 of the 20 pain regions in the brain were already active in the newborns.
Despite having two fewer active pain regions, the experiment suggests babies could have a lower pain threshold than adults.
Scans demonstrated that the babies' brains responded to a weak poke of a force measuring 128 millinewtons (mN) in a manner identical to the adults' brains upon exposure to a force four times stronger, measuring 512mN.
"Thousands of babies across the UK undergo painful procedures every day but there are often no local pain management guidelines to help clinicians," says Dr. Rebeccah Slater of Oxford. "Our study suggests that not only do babies experience pain but they may be more sensitive to it than adults."
The study may have implications for the practice of neonatal circumcision -- the removal of the skin surrounding the glans of a baby boy's penis, called the foreskin -- often performed in the US without anesthetic.
As recently as the 1980s it was common practice for babies undergoing surgery to be given neuromuscular blocks but not pain relief medication, according to the researchers.
A 2014 review of neonatal pain management practice says that babies in intensive care are subjected to an average of 11 painful procedures per day and 60% of them are not given any kind of pain medication.
"We have to think that if we would provide pain relief for an older child undergoing a procedure then we should look at giving pain relief to an infant undergoing a similar procedure," says Dr. Slater.
The study was published in the journal eLife.