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Infections in Preemies Can Have Lasting Effects

Study finds higher risk of neurodevelopmental problems

TUESDAY, Nov. 16, 2004 (HealthDayNews) -- Infections in the smallest premature babies may have long-lasting consequences.

According to a study in the Nov. 17 issue of the Journal of the American Medical Association, infections in extremely low birth-weight infants are associated with impaired cognitive development and physical growth problems.

"We linked neonatal infections to an increased risk for neurodevelopmental outcomes, such as cerebral palsy and low [cognitive] scores," said one of the study's authors, Dr. Barbara Stoll, chair of pediatrics at Emory University School of Medicine in Atlanta.

"Infection is a serious complication that increases the risk of an already vulnerable population," she added.

Unfortunately, infection is also a common complication for premature infants. And ironically, many of the interventions that help to save premature infants, such as ventilators and intravenous lines, can increase their risk of infection.

"Artificial instruments increase the risk for infection," said Dr. Michael Msall, chief of developmental and behavioral pediatrics at the University of Chicago Children's and LaRabida Children's hospitals. Msall wrote an editorial about the Stoll study in the same issue of the journal.

Using data from the National Institute of Child Health and Human Development Neonatal Research Network, collected from 1993 through 2001, Stoll and her colleagues identified 6,093 babies in the extremely low birth-weight category. A baby weighing less than 1,000 grams (about 35 ounces) at birth is considered extremely low birth-weight.

The researchers then followed up when the babies were 18 to 22 months' gestational age to see if they had cerebral palsy and to test the infants' psychomotor skills and to administer a test called the Bayley Scales of Infant Development II.

Sixty-five percent of the babies in the study had at least one infection while they were in the hospital. Overall, 41 percent of the infants -- both those who had an infection and those who did not -- suffered from at least one neurodevelopmental problem.

Because prematurity itself increases the odds of complications such as cerebral palsy, Stoll said the researchers attempted to control for other factors known to increase the risk of neurodevelopmental problems. After adjusting for those other factors, the researchers found the association between infection and neurodevelopmental problems was still present.

The odds of an infant who had at least one infection developing cerebral palsy were between 40 percent and 70 percent greater than a baby who didn't suffer from infection. The odds of having a low Bayley score, which measures mental development, were 30 percent to 60 percent higher for a baby who had an infection. The odds of impaired psychomotor development were 50 percent to 240 percent more likely in a premature baby who had suffered from at least one infection, and vision problems were also more likely. The odds of vision impairment in a baby with a past infection were 30 percent to 220 times as high as they were for infants with no infections.

A history of infection was also associated with less head growth, a known risk factor for neurodevelopmental problems, according to the study.

Stoll said she doesn't know exactly why an infection would cause these problems, but speculated that the inflammatory response the body mounts against an infection to fight it off may somehow disrupt the normal development of the brain. She also speculated that infection could cause cardiac or pulmonary problems that might affect the brain.

Dr. Judith Klarr, an attending neonatologist at William Beaumont Hospital in Royal Oak, Mich., said, "I think this study confirms something we already know: Babies who get infected don't do as well. One of the things this study points out is that there is still a high level of neurodevelopmental disability in both groups."

Said Msall: "There have been major advances that led to the survival of very tiny babies. But there's also been concern that with the increased survival we have to make sure that severe disability is lessened. And this study points out that there's another factor with respect to cognitive disability -- the role of infection."

Stoll, Msall, and Klarr said the study's findings pointed to the need for increased vigilance in infection prevention as well as the need for neurodevelopmental support programs and continued follow-up for these tiny infants.

More information

To learn more about the health problems premature infants might face, read this information from the American Academy of Pediatrics.

SOURCES: Barbara Stoll, M.D., chief of pediatrics, Emory University School of Medicine, Atlanta; Michael Msall, M.D., chief, developmental and behavioral pediatrics and professor of pediatrics, Pritzker School of Medicine, University of Chicago Children's and LaRabida Children's Hospitals, Chicago; Judith Klarr, M.D., attending neonatologist, William Beaumont Hospital, Royal Oak, Mich.; Nov. 17, 2004, Journal of the American Medical Association
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