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Do Newborns Remember Pain? You Bet!

These remarkable findings demonstrate why we need to provide adequate pain control for newborns.

Many newborns are subjected to painful tests, especially in the newborn intensive care unit. In a prospective study of Canadian newborns, investigators examined whether repeated painful stimuli resulted in the anticipation of pain or hyperalgesia.

Full-term newborns with uncomplicated births were compared with full-term infants who were born to diabetic mothers (IDMs) and had undergone repeated heel-stick studies in the first 24 hours of life. Both groups underwent skin cleansing with alcohol swabs followed by venipuncture for genetic screening at 24 hours of age. Videotapes of the venipunctures were graded for signs of infant pain (grimacing, overall facial and body language, and crying time).

The IDM group exhibited significantly more grimacing in response to the alcohol swabs, suggesting anticipation of pain, and also demonstrated significantly more pain from the venipuncture on each of the 3 pain measures. To see whether maternal diabetes had an independent influence on the results, a second cohort of control newborns and IDMs who had not yet received any heel lances were assessed for response to pain from an intramuscular injection of vitamin K; there were no differences between the two groups in signs of pain in response to the injections.

Comment: This interesting study confirms that newborns recall pain and that repeated painful stimuli result in hyperalgesia within 24 hours. The neutral stimuli of alcohol swabs conditioned infants to anticipate pain. These results further emphasize the need for adequate pain control in newborns and indicate that a conditioned response may cause newborns to exhibit pain without an apparent cause. Additional studies are required to determine how long the conditioning lasts.

— F. Bruder Stapleton, MD

Published in Journal Watch Pediatrics and Adolescent Medicine September 9, 2002

Citation(s):

Taddio A et al. Conditioning and hyperalgesia in newborns exposed to repeated heel lances. JAMA 2002 Aug 21; 288:857-61.

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