Babies who underwent repeated heel sticks during the first day and a half of life behaved differently than their peers when they later needed a blood draw from the hand. The experienced babies got upset even during the wiping of the hand before the blood draw. They also demonstrated more pain during the blood draws, with more crying and more grimacing.
We know from other studies that babies can learn and remember beginning months before they are born. Preventing and treating pain in newborns might decrease the pain they experience later.