Abstract
During the years 1969-71 an increased incidence of massive pulmonary haemorrhage among early neonatal deaths in the United Oxford Hospitals was noticed. When compared to an earlier survey in the same hospitals no change in the distribution by birthweight score of the affected infants was seen. The increased incidence of the syndrome coincided with a fall in the perinatal mortality rate. An analysis of the clinical features and pathological findings in the affected infants showed that certain known causes of the syndrome, like antepartum haemorrhage and hypothermia, were still present. In 7 of the 11 cases, however, there was histological evidence of oxygen toxicity. It is suggested that the use of high concentrations of oxygen contributed to the increased incidence of the syndrome.