Trends in postneonatal mortality in the United States. 1962 through 1978.

Trends in postneonatal mortality (PNM) rates in the United States were analyzed for the period 1962 through 1978 using National Center for Health Statistics birth and death certificate data. The PNM rates declined from 5.5 to 3.6 per 1,000 live births for whites and from 15.6 to 7.6 per 1,000 live births for blacks. Most of the decline in PNM rates could be accounted for by a drop in mortality from infectious diseases. A dramatic increase occurred in the reported rates of unexplained sudden infant death (SID), which emerged as the leading reported cause of PNM. The second leading cause of PNM was birth defects among whites and infectious diseases among blacks. Gaps in PNM continued to exist between whites and blacks, and between metropolitan and nonmetropolitan areas. These gaps suggest that further improvement in PNM may be possible by improving access to health care. The massive increase in the rates of SID, although partially explained by coding or reporting phenomena, warrants active pursuit for a better pathophysiologic and etiologic delineation of the entity.