Anomalies associated with pulmonary hypoplasia.

We reviewed the records of 756 consecutive newborns autopsied over a 10-yr period. Using published standards for normal lung weights, low lung weight for total body weight was determined to be a reasonable estimate of pulmonary hypoplasia. Seventy-seven infants with pulmonary hypoplasia were identified. Multiple congenital malformation syndromes were found in the majority of infants with pulmonary hypoplasia. These included major diaphragmatic anomalies, renal anomalies, chromosomal disorders, extralobar pulmonary sequestration, severe musculoskeletal disorders, and isolated right-sided cardiac lesions. Ten infants had no known associated anomalies. The various theories of pathogenesis of pulmonary hypoplasia are reviewed and the suggestion is made that the cause of pulmonary hypoplasia in newborns may well be multifactorial. Various theories of pathogenesis are discussed ranging from an actual lack of space for the lungs to grow, to the possible necessity for appropriate respiratory movement during intrauterine life, to the possibility, particularly in the case of Potter's syndrome, of a primary mesodermal defect affecting multiple organ systems.