Development of EEG and daytime sleep patterns in low risk premature infants during the first year of life: longitudinal observations.

Long daytime EEG-polygraph recordings were obtained at 36, 38, and 40 weeks conceptional age, weekly thereafter for 12 weeks, and at 26 and 52 weeks post term in 5 infants born at 30--33 weeks gestation. The babies have developed normally for 18--38 months. All 74 EEGs were normal for age. Derived data were compared with similar data from 17 normal full-term infants. The tracé alternant pattern disappeared earlier in the premature than in the control group (mean ages 21.4 vs. 33.4 days post appeared earlier in the premature group (mean ages 35.4 vs. 43.8 days; P < 0.05). There were no age differences between the groups with respect to (1) the shift from active sleep onset to quiet sleep onset, (2) active sleep and quiet sleep as percentages of total sleep time, or (3) disappearance of frontal sharp waves. Overall attainment of "infantile" EEG sleep patterns occurred at 35--60 days post term (mean 43.8) for the permature group and at 27--66 days (mean 46.4) for the full-term group (difference not significant). These findings indicate that no significant errors will be made in clinical practice by applying the same maturational criteria to the post-term EEGs of prematures as to the EEGs of full-term infants.