OBJECTIVE To evaluate electroencephalogram (EEG) patterns in very low birth weight premature newborns when reaching term-to-term neonates, thereby comparing extra uterine to intra uterine development. METHODS EEG recordings were obtained between 2 and 14 days of life in 47 preterm (<37 weeks) very low birth weight (⩽1500 g) newborns and repeated when reaching term age (38-42 weeks) in a subsample (n=22). EEG recordings were also obtained in term newborns. Clinical evaluation was performed at birth and at 6 and 12 months. RESULTS Relative to the first EEG, preterm newborns showed a reduction in delta brushes and interburst intervals and increased interhemispheric synchrony, suggesting an improvement in EEG maturation. Further organization in sleep patterns, like a reduction in total sleep time and phase shifts, were also observed. However, when reaching term, preterm newborns still had less mature EEG patterns, phase shifts and transitional sleep than matched controls. Background abnormalities and dysmaturity in preterm newborns during the first EEG predicted adverse neurological outcome later on. CONCLUSIONS EEG patterns in preterm very low birth weight newborns might be influenced by extra uterine development. Specific EEG abnormalities are related to increased risk of neurological disorders. CONCLUSIONS Extra uterine development of very low birth weight delays the acquisition of maturational EEG patterns.