The intensive care treatment premature babies receive after birth sensitises them to pain, research has suggested.
Pre-term infants that have spent 40 or more days in hospital feel pain more acutely than healthy newborns, tests have shown. Researchers writing in the journal NeuroImage claim premature babies should receive better pain relief to prevent them becoming pain-sensitive.
Premature babies are subject to a number of painful procedures, including injections, tube feeding and blood tests, in the months they can spend in intensive care.
An electroencephalogram (EEG) was carried out on the brain activity of babies, along with routine heel lancing to draw blood samples. Premature babies that had been in hospital at least 40 days had stronger EEG traces than non-hospitalised babies of a comparable age.
Brain activity seen when both sets of babies are gently touched on the heel showed no difference, suggesting that the sensitisation of pre-term babies is specific to pain.
The Medical Research Council-funded study supports previous evidence of increased pain sensitivity in older children who were born prematurely.
Research leader Dr Rebeccah Slater, from University College London, said: "Our ability to measure brain responses to painful events will lead to a better and more informed approach to the administration of analgesia, and enable us to define optimal ways of providing pain relief in this vulnerable population."