Background Electroencephalography (EEG) changes rapidly with maturation of the brain in preterm infants. Amplitude-integrated EEG (aEEG) becomes more continuous, bandwidth narrows, and frequencies switch towards faster rhythms, as the child grows older. In preterm infants with brain damage this maturation is typically delayed. We are in the process of developing a preterm piglet brain model. Here we present the results of the EEG as a measurement of brain development in 1–11-day-old preterm and term piglets.

Methods One hour of EEG was recorded in 31 preterm piglets aged 1, 2, 4 and 11 days and in 10 term piglets aged 2 and 11 days. All piglets were delivered by C-section at either 90% or 100% gestation. Upper and lower margins of the aEEG band were visually identified and bandwidth calculated as the difference between the two values. Spectral analysis of the raw EEG was used to determine the relative power in the delta-(0.5–3 Hz), theta-(4–7.5 Hz), alfa-(8–12.5 Hz), and beta-(13–30 Hz) bands. General linear models were used with term vs. preterm, and age as predictors.

Results All aEEGs were continuous. The overall means (SD) of upper and lower margin, and bandwidth were 7 mcV (1.7), 15 mcV (5.7), and 8 mcV (4.3). Upper-, lower margin, bandwidth, alpha, beta and delta bands were unaffected by the predictors whereas the theta band was negatively correlated to age.

Conclusions The preterm piglet EEG was continuous already 10 days prior to term. Thus, maturation of EEG was neither seen in preterm nor term piglets and EEG may not be useful for studying perinatal brain maturation.