Infant mortality decline in the late 19th and early 20th centuries: the role of market milk.

Starting in the late 19th and early 20th centuries, a precipitous decline in infant mortality was observed in the United States. Economic growth, improved nutrition, new sanitary measures, and advances in knowledge about infant care all contributed to this decline in infant mortality. Little is known, however, about how these individual factors affected disease-specific components of infant mortality over time. Systematic review of historical data suggests that cleaning the market milk supply was the single most important contributor to this decline in both diarrheal and overall infant mortality, and that this development played a far more important role than family income, other sanitary measures, or medical intervention.