Effects of repeated heelsticks on premature newborns

Premature newborns were observed longitudinally while undergoing heelsticks. Behavioral and cardiac measures were taken over 5 tests days. On Tests 1, 3, and 5, the phlebotomist picked up the baby\u27s leg and held it for 10 s and then proceeded to collect blood. This manipulation was geared towards observing whether, over days, babies learned that the pick-up of the leg was predictive of a painful event. Infants\u27 reactions were also observed during the invasive parts of the blood collection. It was hypothesized that if infants increased their reactivity to the leg pickup over days, it would suggest that this neutral event had acquired signal value for the subsequent painful stimulus. If infants\u27 response to the heelstick itself increased over days, this could be due to either maturation, sensitization and/or anticipation. However, if infants decreased their reactivity, it could be due to a specific learning mechanism, Stress-Induced-Analgesia. Results or the leg pick-up yielded a marginally significant cardiac increase on the final test day, suggesting anticipation. Infants demonstrated reliable behavioral and cardiac reactions to the heelstick but no change was observed in reactivity over days. Behavioral pain reactions were positively related with gestational age at Test 1, 2, 4 and 5. A greater number of heelsticks was related to fewer facial reactions at Test 5. Further research needs to be done to specify the nature of anticipation and to separate the effects of gestational age and number of invasive procedures on facial reactivity