Babies in the first 24 to 36 hours of life can learn to anticipate pain, according to a fascinating study published in the August 21, 2002 issue of the Journal of the American Medical Association.
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.