Worldwide, 15 million of the 135 million babies born in 2010 were premature and 1.1 million died, according to the "Born Too Soon" report, which was compiled as part of the United Nations' "Every Woman Every Child" initiative.

The report, three years in the making and written by experts from 11 countries, is intended to draw attention to the problem and attract donations from governments and charities to solve it. The study analyzes preterm births (before 37 weeks of the full 40-week gestation) in 184 nations, more than ever previously studied.

Of the 65 developed countries that have kept reliable data over the years, only Croatia, Ecuador and Estonia have cut their rate of preterm births since the 1990s. In the other 62, despite programs to, for instance, improve pre-natal care and reduce the number of Cesarean sections, premature births increased from an average of about 3 percent to 6 percent.

The lack of progress is caused in part by "myths and misperceptions" on the part of public health agencies, said Dr. Christopher Howson, vice president for global programs at the March of Dimes and an author of the report. The misunderstandings include the notion that preterm births are rare and therefore not a significant problem deserving attention and resources.

"This report dispels that idea," Howson said. "Not only is preterm birth not rare, but it's common and it kills."

But how common, and especially how deadly, varies enormously across the world, producing what Howson calls "an appalling mortality gap." Preterm births account for almost half of newborn deaths worldwide, making it the second leading cause of death in children under the age of 5, after pneumonia.

While more than 90 percent of babies born before 28 weeks in wealthier countries survive, however, in poor countries more than 90 percent die.

Rates of preterm birth range from 4 percent in Belarus to 18 percent in Malawi, and generally track poverty rates, the report found. Nine of the 11 countries with preterm rates above 15 percent are located in sub-Saharan Africa. Comoros and Congo have a rate of 16.7 preterm births per 100 live births; Zimbabwe, 16.6. The U.S. rate is 12 percent, the worst of the G8 countries and 59th of the 65 countries with reliable historical data.

CAUSES OF PREMATURITY

The high rates of preterm births in poor countries reflect the fact that poverty is associated with many of the reasons women to go into labor too soon: inadequate prenatal care, infections such as malaria and HIV, high blood pressure, obesity or underweight, substance abuse including smoking, and diabetes.

But the rich-poor divide is not huge. The preterm rate averages 12 percent in poor countries and 9 percent in wealthier ones. In fact, countries with the lowest rates of preterm births are not the wealthiest. After Belarus, the next-lowest rate is in Ecuador (5.1), followed by Latvia (5.3); Finland, Croatia, and Samoa (5.5); and Japan and Sweden at 5.9.

In richer countries, the causes of prematurity include more older women having babies, multiple pregnancies due to fertility drugs and inductions and Cesarean deliveries done for convenience rather than medical necessity.

"Many women and their doctors pick 37 weeks to induce labor or have a Cesarean," said pediatrician Joy Lawn of Save the Children, an author of the report. But because determining gestational age is an inexact science, many supposedly 37-week babies "might be less than 35 weeks," she said.

Of 500,000 premature births in 2010, the U.S. rate of 12 per 100 live births is more like that of a developing country, ranking 130th of 184 countries, tied with Somalia, Thailand, and Turkey, and only slightly better than Honduras and Timor. Among the reasons, said Howson, is the many older mothers (14 percent of U.S. births are to women 35 or older), fertility drugs (carrying twins, triplets, and more makes preterm birth more likely), and induced labor or Cesareans.

INEXPENSIVE SOLUTIONS

Preterm deaths could be reduced by 75 percent through inexpensive interventions, Lawn said. Among them: teaching mothers to carry their newborns "kangaroo style" on the chest to keep warm. That could save 450,000 preemies a year. Injections of corticosteroids for mothers in premature labor, which help fetal lungs develop, cost $1 each and could save 370,000 babies a year.

Problems loom for many preemies who survive. About 25 percent of those born earlier than 28 weeks are blind or otherwise visually impaired. About 5 percent to 10 percent are deaf, 40 percent have chronic lung disease and an unknown number suffer learning and cognitive impairments.

The ultimate solution — keeping every baby in the womb for 40 weeks - is a challenge. Improving maternal health by treating high blood pressure and infections would help, as would changing obstetrical practices so labor is not induced early for non-medical reasons.

"We still don't know a lot about how to prevent preterm birth," Howson said. "We need vigorous, targeted research into its causes."

The report's sponsors include the March of Dimes; the Partnership for Maternal, Newborn, and Child Health; Save the Children; and the World Health Organization.

Donors are anteing up to reduce the preterm death rate. The Bill & Melinda Gates Foundation has committed $1.5 billion over four years to support interventions such as antenatal corticosteroids and to discover new ones. The March of Dimes is spending $20 million a year for research on the causes of prematurity and to improve access to prenatal care.

The WHO and its partners have set two goals for 2025: eliminating mortality from preterm births in countries where the rate of preterm birth is now less than 5 percent, and halving mortality where it is 5 percent or more.

(Editing by Michele Gershberg and Bill Trott)

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