Until now doctors have believed that the brains of very young babies were not developed enough to feel pain. However, in a new study that overturns the medical consensus, researchers have found that tiny babies actually do feel pain and are more sensitive to pain than adults.

Current medical consensus has meant that very young babies often go without painkillers, even during invasive procedures. However, the new findings revealed by Oxford University doctors suggest that not only do they feel pain, but their pain thresholds are even lower than those of adults.

In the first study of its kind, researchers showed in brain scans that the brains of infants react the same way as adults when given even mild pain.

Dr. Rebeccah Slater, of Oxford's department of Paediatrics, said, "Obviously babies can't tell us about their experience of pain and it is difficult to infer pain from visual observations. In fact some people have argued that babies' brains are not developed enough for them to really "feel" pain, any reaction being just a reflex - our study provides the first really strong evidence that this is not the case."

Up until the 1980s it was common practice to go without pain relief and they were only given neuromuscular blocks to stop them moving. In a study in 1987 it was suggested that for the first time doctors may have been wrong, and anesthetics were introduced for major operations. However, there are still many invasive procedures that are performed without anything administered to remove the pain.

Dr. Slater has called for a review of the way small babies are treated.

"Our study suggests that not only do babies experience pain but they may be more sensitive to it than adults. 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."

Her team scanned the brains of ten healthy infants between the ages of one and six months and then compared them to scans of the brains of ten adults between the ages of 23 and 36 years old. MRI scans were taken of the babies' brains as they were poked on the bottom of their feet with a special retracting rod duplicating the sensation of being poked with a pencil. The poke was mild, however, and not even enough to wake them from sleep.

Scans show that the babies brains had the same response to a weak poke as adults did with a stimulus that was four times as strong, suggesting that the babies' pain thresholds are lower.

Dr. Slater said it isn't clear what type of painkillers should be used for babies. There are fears that some local anesthetics can be easily absorbed into the blood stream and could have unknown consequences for babies. "Finding the optimum pain relief for babies is clearly required," she said.