Epidemiology
Pneumonia occurs frequently in newborn infants, although reported rates vary considerably depending on the diagnostic criteria used and the characteristics of the population under study. Most reports cite frequencies in the range of 5-50 per 1000 live births, with higher rates in the settings of maternal chorioamnionitis, prematurity, and meconium in the amniotic fluid. Many cases are likely unreported or undetected; thus, the cited frequency is almost certainly a low estimate.
Determination of mortality rates among infants with congenital pneumonia is complicated by variations in diagnostic criteria and the thoroughness with which this condition is sought. Among infants with congenital pneumonia associated with proven blood-borne infection, mortality is in the range of 5-10%, with rates as high as 30% in infants with very low birth weight. Pneumonia is a contributing factor in 10-25% of all deaths that occur in neonates younger than 30 days.