Washington (AFP) - Americans' life expectancy has remained unchanged for a third straight year, following decades in which it had steadily risen, according to government statistics published Wednesday.
A child born in the United States last year can expect to live 78.8 years on average -- 81.2 years for females and 76.4 years for males -- said the report from the federal Centers for Disease Control and Prevention (CDC).
The agency also reported a drop in the infant mortality rate in 2014, now at a historic low rate of 5.8 deaths per 1,000 births among children aged 1 year or less.
Life expectancy had stagnated for three years once before, during the 1980s.
But overall, gains in longevity have been almost a constant since World War II, owing primarily to medical advances, improved nutrition and education, and public health policies such as the campaign against smoking.
The causes of the recent plateau in life expectancy are not entirely clear, but several experts say that a sharp increase in deaths from illegal drug use, as well as suicides, could be factors.
A study published in November by the American Angus Deaton, a 2015 Nobel Prize laureate, suggests that mortality among middle-aged white Americans, which had been declining since 1978, has been on the rise for 15 years because of alcohol and drug abuse and suicides, particularly among the disadvantaged.
While some researchers have pointed to the sharp rise in obesity as a mortality factor, the CDC said there was no data for now to support that view.
The US trails nearly 40 countries in a World Bank longevity ranking. Japan and Iceland top the chart, with life expectancy of 83 years, ahead of France and Sweden, at 82 years, and Canada at 81.
The chief causes of US mortality (73.8 percent of all deaths) are unchanged from last year, in descending order: cardiovascular disease, cancer, chronic respiratory ailments, accidental injuries, strokes, Alzheimer's disease, diabetes, influenza, pneumonia, kidney disease and suicide.
Deaths by cardiovascular disease were down by 1.6 percent, and those by cancer declined 1.2 percent.
But deaths from Alzheimer's, affecting the growing population of aging Americans, were up 8.1 percent, and deaths by suicide and accidents rose 3 percent.