WASHINGTON — About one in every 10 babies is born prematurely each year worldwide, and more than one-quarter of deaths that occur in the first month — about 1 million — are the consequence of preterm birth.
Those are among the findings of a study of the burden of preterm birth by the World Health Organization and the March of Dimes.
The global health community is focusing renewed attention on maternal-child illness and mortality. The new study, to be followed by a country-by-country assessment next year, looks at the specific role of prematurity in the problems of newborns.
“These are striking data that really surprised us,” said Christopher Howson, a March of Dimes researcher who helped prepare the report.
About 12.9 million babies are born too soon each year, representing 9.6 percent of births. Of the 4 million deaths that occur soon after birth, 28 percent are attributable to prematurity.
And women expecting more than one child have a much greater risk of delivering early.
“We know the figures in this report are conservative,” Howson said. “I think we can say very clearly that the situation on the ground is more dire than this suggests.”
Preterm birth is defined as birth before 37 weeks of gestation. A typical pregnancy lasts 40 weeks. Rates and causes of preterm birth vary widely by region.
Africa has the highest rate (11.9 percent), followed by North America (10.6 percent) and Asia (9.1 percent). Latin America and the Caribbean are midrange (8.1 percent), and Australia and New Zealand (6.4 percent) and Europe (6.2 percent) are the lowest.
Relatively little is known about the causes of prematurity in the developing world. However, malnutrition, coexisting illnesses such as malaria and anemia and inadequate prenatal care are likely factors, Howson said.
Other variables are probably at play in the United States, where the rate of preterm birth has increased 36 percent in the past quarter-century. (It stands at 12.7 percent; the North American rate is brought down by Canada’s 8.2 percent rate.)
The increase in older women having babies and reproductive techniques that make multiples more likely are probably contributing to the trend. Black women have a 50 percent higher rate of preterm delivery than whites.
