The rate of premature births in the United States fell by 11.7 per cent in 2011 to the lowest level in a decade, a study published Tuesday said.
"These results demonstrate that many premature births can be prevented with the right policies and bold leadership," said Jennifer Howse, president of the March of Dimes, which released the study.
"We must implement proven interventions and accelerate our investment in new research to prevent preterm birth so one day every baby will get a healthy start in life," she said.
She said the progress, besides resulting in better health for newborns, should translate into about $3 billion in savings in medical care and other costs to society.
The rate of premature births peaked in 2006 in the United States after rising over the previous 20 years, according to the National Center for Health Statistics.
The rate has fallen for five consecutive years, with the biggest declines seen in babies born between 34 and 36 weeks of gestation. The decline in premature births has occurred across all ages and racial and ethnic groups.
About 15 million babies are born prematurely each year around the world and about a million of those die, the March of Dimes said, citing a report published in May 2012.
Despite the improvement over the past five years, the United States still ranks 131st out of 184 countries in terms of premature birth rates.
Among the poorest countries, 12 per cent of babies are born prematurely -- at less than 37 weeks -- compared to nine per cent in rich countries.
The March of Dimes has set a goal of lowering rates of premature births in each US state to 9.6 per cent by 2020.