The study found newborn babies of diabetic mothers had been sensitised to the sharp pain that comes with being jabbed in the foot with a needle after just 24 hours of life.

By that time the babies had had blood taken several times so physicians could monitor their blood glucose level.

So when these babies were being prepped for routine blood collection at the one-day mark, they reacted more intensely than regular babies because they recognised the cues that went with the procedure.

The babies grimaced much more than the normal infants when the back of their hands were being cleansed in preparation for the venipuncture -- in which blood is taken from the back of the infant's hand for routine disease-screening purposes -- than the babies of non-diabetic mothers.

And they grimaced, squirmed and cried much harder during and after the procedure than the control babies.

"We suggest that throughout the course of repeated exposure to skin cleansing followed by heel lancing, skin cleansing became a conditioned stimulus, reliably signaling the impending painful event and inducing anticipatory pain behaviors and possibly even pain," wrote Anna Tadio, an assistant professor of pharmacy at the University of Toronto.

The findings suggest doctors should find more effective ways of managing neonatal pain during invasive procedures to prevent them becoming extra-sensitive to pain, they added.

The study of 42 babies was conducted by researchers at the University of Toronto's Hospital for Sick Children, and appears in Wednesday's edition of the Journal of the American Medical Association.

(Xinhua News Agency August 21, 2002)