WHITE PLAINS, N.Y., AUG. 16, 2000 -- Babies born only a few weeks prematurely are at increased risk of dying in the first month or year of life, according to a study published today in The Journal of the American Medical Association.
While most researchers have focused on very premature babies, Michael S. Kramer, M.D., of the Departments of Pediatrics and of Epidemiology and Biostatistics, McGill University, Montreal, a research grantee of the March of Dimes, and colleagues studied the health records of several million U.S. and Canadian babies born as little as one week prematurely. Dr. Kramer and his team were surprised to learn that these babies had a significantly increased risk of dying, especially from asphyxia and infection, compared to full-term babies. Babies born even mildly premature are more than twice as likely to die in infancy.
Preterm birth is defined as less than 37 full weeks' gestation. Mild prematurity was defined in the study as 34 through 36 completed weeks' gestation, while moderate prematurity was defined as 32 through 34 completed weeks' gestation. Less than 32 weeks' gestation is considered very premature.
"Every day of development during pregnancy is precious to the health of an unborn baby," says Jennifer L. Howse, Ph.D., president of the March of Dimes. "This finding that just a few days' prematurity is associated with higher risk of death gives even greater urgency to our efforts to find ways to prevent preterm birth from occurring."
"Births at gestational ages of 32 through 36 weeks are much more common than those at less than 32 gestational weeks," the authors point out, concluding that, "Preventing the occurrence of mild and moderate preterm births and of death among such births remain worthy targets for future research and clinical intervention."
Dr. Kramer is one of six prominent researchers in the area of preterm birth to receive March of Dimes Perinatal Epidemiological Research Initiative (PERI) grants. The March of Dimes has awarded nearly $4 million in grants in this unique project to investigate biological and environmental factors that may contribute to the more than 400,000 preterm births in the U.S. each year.
There is a well-known link between lower socioeconomic status and a higher risk of preterm birth. With his PERI grant, Dr. Kramer is examining two possible pathways by which low income and education may result in preterm delivery. "Having less money or education probably has no direct effort on the duration of pregnancy. Instead, it probably leads to unhealthful behaviors, exposure to stress, and reactions to stress that shorten pregnancy," he says. Dr. Kramer is focusing first on the mental stress of poverty and a lack of education and resources. He will then examine whether some women are more vulnerable to the effects of a diet lacking certain important nutrients.
"The Contribution of Mild and Moderate Preterm Birth to Infant Mortality," by Michael S. Kramer and colleagues of the Fetal and Infant Health Study Group of the Canadian Perinatal Surveillance System, was published in the August 16, 2000 issue of JAMA, volume 284, number 7.
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The March of Dimes is a national voluntary health agency whose mission is to improve the health of babies by preventing birth defects and infant mortality. Founded in 1938, the March of Dimes funds programs of research, community services, education, and advocacy to save babies. More information is available on the March of Dimes Website at http://www.modimes.org.
Journal
JAMA