Delivery decisions are made by physicians and patients after careful consideration of all relevant medical factors.

The researchers have found other discrepancies in official death reports that seem to correlate with social rather than medical factors.

"One third of the total inpatient days and over 20 percent of the cost resulted from social rather than medical factors."

Will social factors be given equal weight with medical factors when determining such claims?

This disparity is complex and cannot be explained solely by medical or socioeconomic factors.

The answers, experts say, lie in a tangle of medical, racial and economic factors.

There are also a number of genetic, medical and psychological factors that play a part in the nation's culture of obesity.

Others wonder whether a combination of social and medical factors could spare the country from a runaway epidemic.

Sport is too often regarded as a playful activity and not a vital social, medical, cultural or economic factor.

Substantial differences in death rates could not be explained solely by demographic and medical factors, the study found.