Variation in power spectral analysis of the EEG with gestational age.

Power spectral analysis (PSA) of the EEG was studied in healthy term and preterm neonates to establish the normal range with gestational age. Sixty healthy newborn infants from 26 to 41 weeks' gestation had PSA performed at 3 days of age. Five main frequency bands were studied: delta 1 (1 Hz or less), delta 2 (2-3 Hz), theta, alpha, and beta. A significant correlation was shown between absolute power in delta 1 and delta 2 with gestational age. Relative power of each frequency band, calculated as a percentage of the total power in each channel, also correlated with gestational age. A significant quadratic relationship between absolute power in the beta range and gestational age is described for the first time.