The purpose of this investigation was to examine longitudinally gestational age and developmental differences in preterm infants' self-regulatory abilities in response to a painful stressor, as well as associations between behavioral and cardiovascular responses. Participants included 49 healthy premature infants. Behavioral and cardiovascular responses to a heel stick blood draw were compared between infants of 28-31 and 32-34 weeks' gestation age at birth. Both gestational age groups displayed behavioral and cardiovascular indications of stress in response to the blood draw. However, both shortly after birth and several weeks later, infants born at younger gestational ages (28-31 weeks) were more physiologically reactive. Evidence that the behavioral stress responses of 28-31 weeks' gestation age group preterm infants do not reflect their physiological responses suggests that evaluation of preterm infants' experiences and risk require assessments of both physiology and behavior. The greater stress vulnerability of the 28-31 weeks' gestation group relative to the 32-34 weeks' gestation group and the implications of this for subsequent development are discussed.
Bibliographical noteFunding Information:
This research was supported by a grant from the Minnesota Medical Foundation (643-7051) to the last author and a K05 award (MH66208) to the third author. The authors wish to give a very special thank you to the families who participated in this research and to the nurses, lab technicians, and physicians at the Fairview University Medical Center and Hennepin County Medical Center, Minneapolis, MN. Thanks also to the undergraduates at the University of Minnesota who assisted with data collection for this study.
- Physiological reactivity