Prematurity Causes a Third of Infant Deaths
At least a third of infant deaths in the United States are the direct result of prematurity, double the proportion previously believed, federal researchers report today.
Prior data obtained solely from death certificates had indicated that birth defects were the major cause of death among infants in their first year.
But linking death certificates with birth certificates, which include gestational age, shows that birth before 37 weeks of gestation plays the dominant role, according to the study. A full term is 38 to 42 weeks.
Prematurity is the direct cause of death for half of those who die in the first month of life, and also for 95% of those who are delivered before the 32nd week of pregnancy, according to the report in the journal Pediatrics.
“What this says is that we need to focus a lot more effort on prevention and the study of what leads to prematurity,” said Dr. Gabriel Escobar of the Kaiser Permanente Division of Research in Oakland, who was not associated with the study.
“In the United States, the death rate in term babies without congenital anomalies is approaching zero,” he said. “If we want to save babies, we have to focus on preemies.”
And that means focusing on the mothers, said the study’s leader, Dr. William M. Callaghan of the Division of Reproductive Health at the Centers for Disease Control and Prevention.
“We are approaching the limits of technology to keep the infants alive,” he said.
“If anything is going to be done to make a major movement, it’s the prevention of preterm births.”
One in eight infants born in 2004 -- the most recent year for which figures are available -- was premature, a 30% increase over the rate in 1980, according to a National Academy of Sciences report issued this summer.
The reason for the increase is unknown.
The rate of prematurity is lowest in whites, slightly higher in Hispanics and highest in African Americans, said Joann Petrini, director of the March of Dimes Perinatal Data Center. “But the rates are increasing for everyone,” she said.
The mortality rate, which declined for several decades, stabilized at about 6.8 deaths per 1,000 births in 1999 -- a rate substantially higher than in other industrialized countries.
Preterm children cost the nation about $26 billion a year. Some of them, particularly the earliest-born, have severe behavioral and physical disabilities.
Callaghan and his colleagues studied 27,970 infant deaths in 2002 for which both birth and death certificates were available and linked.
To simplify their study, they focused on deaths that had been attributed to 20 leading causes of infant death, including birth defects, respiratory distress and cardiac problems.
They concluded that 9,596 deaths -- or 34.3% of total deaths -- were a direct result of preterm birth.
Escobar said the findings showed that more research was needed on the causes and prevention of prematurity.
“Every day that you keep a baby in that womb makes a difference,” he said.
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