Biobehavioral pain responses in former extremely low birth weight infants at four months' corrected age

Objective. To compare biobehavioral responses to acute pain at 4 months' co rrected age between former extremely low birth weight (ELBW) infants and te rm-born controls. Methodology. Measures of facial behavioral and cardiac autonomic reactivity in 21 former ELBW infants (mean birth weight = 763 g) were compared with t erm-born infants (n = 24) during baseline, lance, and recovery periods of a finger-lance blood collection. Further, painful procedures experienced dur ing neonatal care were quantified in both groups. Results. Overall, behavioral and cardiac autonomic responses to the lance w ere similar between groups. However, the ELBW group seemed to have a less i ntense parasympathetic withdrawal in the lance period and a more sustained sympathetic response during recovery than the control group. Further, in th e recovery period, two behavioral patterns (early recovery and a late recov ery) were apparent among the ELBW group. Conclusions. Biobehavioral pain responses were similar overall between both groups of infants. Subtle differences were observed in cardiac autonomic r esponses during the lance period and in behavioral recovery among ELBW infa nts. Whether these findings represent a long-term effect of early pain expe rience or a developmental lag in pain response remains unclear. The lack of an overall difference runs counter to previously reported findings of redu ced behavioral response in former ELBW infants.