WASHINGTON (AP) -- They call it kangaroo care: A premature baby nestles skin-to-skin against mom's bare, warm chest. In Malawi, mothers' bodies take the place of too-pricey incubators to keep these fragile newborns alive.

Nearly one in 10 of the world's babies is born premature, and about 1 million infants die each year as a result, says a startling first attempt to measure a toll that in much of the world is hidden.

It's a problem concentrated in poor countries, with the vast majority of the nearly 13 million preemies born each year in Africa and Asia, according to the report released Sunday by the March of Dimes.

But take a closer look at the proportion of all babies born too early. Those rates are highest in Africa, but followed closely by North America, concludes the first part of a collaboration with the World Health Organization to tackle the growing problem.

How? "That's the 13 million-baby question," said March of Dimes epidemiologist Christopher Howson, who headed the project being debated this week at a child health meeting in India.

Different factors fuel prematurity in rich countries and poor ones. Wealthy nations such as the United States have sophisticated neonatal intensive care units for the tiniest, youngest preemies. That produces headlines about miracle babies and leads to a false sense that modern medicine conquers prematurity -- without acknowledging lifelong problems including cerebral palsy, blindness and learning disabilities that often plague survivors.

Scientists don't even know all the triggers for preterm birth or how to stop early labor once it starts, one reason that the report urges major new research. Nor does much of the world even track how many babies are born too soon, why or what happens to them.

"These are conservative estimates," Howson said. "As shocking as this toll is, that toll will only rise" as next year the WHO finishes a more in-depth country-by-country count.

Yet even in very poor countries, there are steps to improve preemies' survival if only more mothers knew, said Dr. Joy Lawn, a pediatrician-turned-policy director for Save the Children who is based in South Africa.

"Even in educated families, there's a sense of fatalism if a baby is born preterm. There's no expectation they can do anything," Lawn said. "With pretty simple solutions, these deaths could be halved, but it doesn't seem to be a priority."

She points to Malawi, where traditionally new mothers have tied babies to their backs as they go about their day. Today, mothers of preemies are taught to tie them in front, under their clothes, kangaroo care-style, she said. The skin-to-skin contact keeps the infants' body temperature more stable, a key to survival, and they can nurse at will, promoting weight gain.

Now Uganda is starting to teach kangaroo care.

Babies born before completion of the 37th week of pregnancy are premature. The March of Dimes report found a small fraction in the U.S. are born before 32 weeks, the very early preemies who face the greatest risk of death and lifelong health problems. But even being born a few weeks early can lead to breathing problems, jaundice and learning or behavioral delays.

Among the risk factors:

--Lack of prenatal care to be sure the mother-to-be is adequately nourished and getting proper care for pregnancy-harming conditions such as diabetes, high blood pressure or infections.

--Smoking and alcohol use.

--Pregnancy before age 16 and after 35, or pregnancies spaced too closely, less than two years apart.

--Carrying twins or more.

--In wealthy nations, early elective inductions and cesarean sections.

Sunday's report is believed the first region-by-region estimate of prematurity, but it undercounts the problem by examining only singleton births to mostly healthy women, Howson said. As a result, it estimates 480,000 preemies are born in the U.S. and Canada each year when more precise U.S. government figures put that total at more than half a million in this country alone.

Whatever the precise number, the point is to increase research into the problem and note the simple steps to lessen preventable risks today, Howson said.

"What leads to a healthy outcome or adverse outcome are factors that begin far before that third trimester," he said, stressing care for infections and chronic conditions, better diet and family planning so the mom-to-be is healthier before she conceives. "We as an international community must think more upstream."

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