Abstract: Objective：To investigate the characteristics of amplitude integrated electroencephalogram(aEEG) at early stage after birth in preterm infants of different gestational ages(GA).Methods：From January 2014 to December 2016, 209 preterm infants of different gestational ages were treated in the First Affiliated Hospital of Sanming of Fujian Medical University, who were divided into 6 groups according to the gestational age. NicoletOne brain function monitor was used to monitor the changes of aEEG within 24 hours after birth. The aEEG background continuity,sleeping-waking cycle, lower boundary voltage amplitude and bandwidth of the narrow band were retrospectively analyzed to study the regularity of the changes.Results：The aEEG wave form continuity of 209 preterm infants showed that: (1)In the group with GA<28 weeks, all of them were highly discontinuous,and with the increase of GA, the proportion of continuous voltage gradually increased. There was significant difference among the groups(P<0.01). (2)There was no noticeable changes in the sleep cycle in the group with GA<28 weeks. With the increase of GA, the frequency of sleep cycle gradually increased and matured, and there was a significant difference among the GA groups(P<0.01). (3) With the increase of GA, the amplitude of the lower boundary of the spectral band increased. The difference in the amplitude of the lower boundary among the groups of preterm infants was statistically significant(P<0.01); the bandwidth tended to become narrow. The difference among the groups of preterm infants was statistically significant(P<0.01).Conclusion：The aEEG shows some specific regularity at different GA in preterm infants，which provides a certain reference for clinical judgment of brain function in premature infants.

Key words: Premature infants, Amplitude integrated electroencephalogram, Gestational age, Brain function