Causes of death in the extremely low birth weight infant.

OBJECTIVE: To present primary and secondary causes of death confirmed by autopsy for the extremely low birth weight infant.

METHODS: A total of 111 infants weighing between 300 and 1000 g at birth who died and were autopsied at our hospital during the 4-year period 1990-1993 were retrospectively reviewed. Clinical, pathologic, and laboratory data were retrieved including results of placental examinations and autopsy cultures. Primary and secondary causes of death were assigned by the authors.

RESULTS: Infection was the most common primary cause (56/111) followed by respiratory distress syndrome/bronchopulmonary dysplasia (24/111) and congenital defect (15/111). Immaturity as an only cause appeared almost exclusively in infants weighing <500 g at birth. Infection was significantly underdiagnosed clinically with most of these deaths attributed to immaturity or respiratory distress syndrome. In only 1 case was intraventricular hemorrhage considered the primary cause of death although it was present as a secondary cause in 19/111. Infections were divided into congenital (30/56) and acquired (26/56) by time of death. The congenital infections (</=48 hours) consisted of pneumonia and chorioamnionitis/funisitis attributable to maternal enteric organisms. Causative bacteria were obtained in pure culture in a number of these cases. The acquired infections were mainly caused by yeasts and nosocomial bacteria. Sixty-seven percent of the deaths occurred in the first 2 days and 12% were beyond the neonatal period at 29 to 104 days. Care was not initiated or was withdrawn in 50% of the infants, usually within the first 4 hours.

CONCLUSIONS: Infection of the amniotic fluid leading to pneumonia was the major cause of death in the extremely low birth weight infant. Accurate cause of death can not be reliably ascertained without an autopsy accompanied by examination of the placenta in the early deaths. Antibiotic treatment of the mother and infant may have reduced the deaths from infection. Early failure to respond to neonatal intensive care may well indicate presence of a congenital pneumonia.