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Journal Issue: Children with Disabilities Volume 22 Number 1 Spring 2012

Childhood Health: Trends and Consequences over the Life Course
Liam Delaney James P. Smith

Global Trends in Childhood Health

Robert Fogel documents historical shifts in patterns of health through three periods: first, where infant mortality is high and life expectancy low, largely because of food shortages; second, where, although improved from the first stage, infant mortality remains high and life expectancy remains low because of infectious diseases; and third, where infant mortality falls and life expectancy increases significantly as major infectious diseases are suppressed by sanitation systems, vaccinations, improved nutrition, and other factors.3

Inadequate sanitation and nutrition are common in poor countries, where an estimated 7.8 percent of childhood deaths are caused by complications arising from below-normal birth weight, 6.6 percent of childhood deaths stem from unsafe sex (that is, sexual behaviors that increase the risk of contracting a sexually transmitted disease), and 6.1 percent arise from unsafe water.4 Globally, the main causes of death among children are pneumonia (17 percent), diarrhea (17 percent), other infections (12 percent), severe neonatal infections (11 percent), premature birth (11 percent), and malaria (7 percent). The main factors implicated in child deaths in developing countries include deficiencies of zinc, iron, and iodine; poor sanitation; suboptimal breast-feeding patterns; and poor nutrition. Worldwide, deaths of children younger than age five dropped from 11.9 million in 1990 to 7.7 million in 2010, with almost half of the percentage decline occurring in sub-Saharan Africa, a third in South Asia, and less than 1 percentage point in high-income countries.5

In the United States, recent work has demonstrated a shift in patterns of childhood illness away from acute health problems and toward chronic conditions. Several recent papers have argued that, contrary to the picture of improving child health suggested by mortality data discussed below, the extent of childhood chronic physical illnesses is increasing in the United States.6

Changing Patterns in the United States
As outlined by David Cutler and Ellen Meara, increasing life expectancy during the first half of the twentieth century was driven largely by substantial declines in infant mortality related to improved sanitation and nutrition, while other factors such as medical improvements contributed mainly to increased life expectancy during the second half of the century.7 Cutler, Angus Deaton, and Adriana Lleras-Muney also documented that declining infant mortality was the most significant contributor to increased life expectancy during the first half of the 1900s.8 While medical advances occurred throughout the late twentieth century in treatments of illnesses affecting infants, infant mortality rates were already so low as a fraction of total mortality that the advances had only small effects on overall life expectancy.

Figure 1 shows trends in infant mortality since the mid-1930s in the United States and in a population-weighted average aggregate of Western European countries that have had comparable data and consistent geographical boundaries.9 In the United States, there was a rapid decline in infant mortality rates, with the 2008 rate falling below 1 percent. Based on variation in timing and location of scientific advances, Cutler and Grant Miller estimated that improved water purification accounted for almost half of the overall mortality reduction and three-quarters of the decline in infant mortality during the first third of the twentieth century in America.10 Cutler and Meara attributed the continuing decline in infant mortality after the 1960s to improvements in neonatal medical care for low-birth-weight babies.11

From the 1930s to 1945, infant mortality rates in Western Europe were higher than in America (see figure 1). During this period, the gap actually widened as the Western European rate stalled, most likely because of the Great Depression and World War II. After the war, Western European infant mortality rates fell rapidly, converged with U.S. rates by the mid-1970s, and then fell slightly below U.S. rates. Still, both U.S. and Western European infant mortality rates are low relative to historical levels and also relative to reported rates of childhood chronic conditions.