preterm infant

stress-coping

neonatal intensive care unit

The purpose of the present study was to clarify the characteristics of stress-coping behavior exhibited by preterm infants, and to investigate the effects of environmental changes on this behavior. A total of 4 premature babies, between 29 and 32 weeks gestational age at birth and free of known developmental risk factors, were studied in a neonatal intensive care unit at a general hospital in Japan. Babies were observed between 33 and 39 weeks gestational age. Data were analyzed using quantitative and qualitative methods. The following results were obtained. 1. Stress-coping behavior in all infants changed over the period from 33 to 39 weeks. At 33 to 35 weeks, infants mainly exhibited rapid sleep state decline or weakened muscle tone. Coping behavior with extremity movements, including self-regulatory behavior, appeared sporadically. At 35 to 36 weeks, the predominant parasympathetic nervous system response began to appear more often. In contrast, coping behavior with extremity movements decreased during week 35, and increased in frequency again during week 36. At 37 to 39 weeks, continuously exhibited‘ specific coping behavior with extremity movements unique to each infant' became apparent and several kinds of continuous selfregulatory behaviors were observed. 2. When environmental changes, such as transfer from incubator to crib, occurred during the transition period of stress-coping behavior in preterm infants, there was a decrease in coping behavior with extremity movements. These findings indicate that it is necessary to consider the possible stressful effects of excessive stimulation from environmental changes on preterm infants.