Serum prolactin (PRL) levels were studied in 28 newborn infants with acute encephalopathy (6 with seizures and 22 without) at the Children’s Hospital of Philadelphia and St Christopher’s Hospital for Children, Philadelphia, PA. Serum PRL was significantly higher at baseline and 15 min postictally in patients with seizures than in the nonictal group, but postictal levels were not different from baseline values. In both groups, patients with abnormal EEG backgrounds had higher PRL levels than those with normal EEG background. 
COMMENT. Newborns with EEG confirmed seizures, but without clinical manifestations, have high base-line serum PRL levels that do not increase postictally. These findings were contrary to those recently reported by Morales et al (1995) who found that only newborns with electroclinical seizures, not those with subclinical EEG seizures, had a significant postictal increase in PRL. Serum PRL levels correlate with the severity of the acute neonatal encephalopathy, as determined by the EEG background changes.