But expert opinion and official treatment guidelines from different organizations are still divided on whether all babies should routinely be tested for the condition.
Infants born at hospitals with universal bilirubin screening had a 62 percent lower incidence of total serum bilirubin (TSB) levels that exceeded limits set by the American Academy of Pediatrics (AAP) than babies born at facilities without universal screening, according to a report in the Sept. 28 issue of Pediatrics.
Babies born at hospitals with routine screening, using a TSB blood test or transcutaneous bilirubin (TcB) skin test, also received twice as much inpatient phototherapy and had slightly longer hospitalizations after birth than other babies.
Bilirubin is a chemical produced when the liver breaks down old red blood cells. It's often elevated in newborn infants.
In rare cases, high levels of bilirubin can cause brain damage (kernicterus), hearing loss, eye muscle problems, physical abnormalities and even death. The incidence of kernicterus ranges from 0.4 to 2.9 per 100,000 live births, according to previous research.
A common treatment for high bilirubin is phototherapy: infants are exposed to bright lights, which trigger processes that change bilirubin into other products that can be passed through their systems.
"Universal bilirubin screening, with either TcB or TSB measurements, was associated with increased identification of newborns needing phototherapy and a significantly lower incidence of severe hyperbilirubinemia," Dr. Michael Kuzniewicz of the University of California San Francisco Children's Hospital, and colleagues wrote.
"There also was a substantial increase in the use of phototherapy, often at bilirubin levels lower than those recommended by the AAP."
The paper by Kuzniewicz and colleagues was one of six articles on bilirubin and hyperbilirubinemia (high levels of bilirubin in the blood) in the September 28 issue of Pediatrics.
Experts Split on Value of Newborn Test
They presented a variety of sometimes conflicting option about the effectiveness of screening all infants for bilirubin -- which is routine at some hospitals but not at others. They also included an update to AAP guidelines and a statement by the U.S. Preventive Services Task Force (USPSTF) on universal bilirubin testing. They came down on opposite sides of the issue.
The USPSTF acknowledged that early treatment can decrease the number of infants with elevated serum bilirubin levels. But it didn't find sufficient evidence that that treating elevated bilirubin levels in term or near-term infants for severe bilirubin buildup actually prevented chronic bilirubin encephalopathy, the most serious danger arising from the condition.
"Evidence about the benefits and harms of screening is lacking," the task force wrote. "Thus, the USPSTF could not determine the balance of benefits and harms of screening newborn infants to prevent chronic bilirubin encephalopathy."
In contrast, a 2004 update to practice guidelines issued by the American Academy of Pediatrics, the AAP Subcommittee on Hyperbilirubinemia supported universal bilirubin screening after every birth, using either TSB or TcB measurements.
The authors acknowledged that the cost-effectiveness and efficacy in preventing kernicterus are unknown.
"Nevertheless, because kernicterus is a devastating condition that leads to serious and permanent neurologic damage, and because published reports and our own review of cases in the medicolegal setting suggest that many of these cases could have been prevented, a reasonable argument can be made for implementing the suggested recommendations in the absence of better evidence," they wrote.
In an accompanying editorial, Dr. Thomas Newman of the University of California, San Francisco, who was also an author on the 2004 AAP guidlines and the new update, wrote that while routine testing is an imperfect tool, it might prevent some cases of brain damage.
"Perhaps partly because I have served as an expert consultant on dozens of heartbreaking kernicterus legal cases, I find the argument in favor of universal bilirubin screening and systematic follow-up persuasive," he wrote.
Testing May Avert Devastating Condition, Some Say
"We know kernicterus is devastating and that, although rare, cases are continuing to occur. Furthermore, anecdotal evidence suggests that many cases could have been prevented by earlier measurement of bilirubin levels, leading to closer follow-up and earlier initiation of appropriate therapy."
In their new study, Kuzniewicz and colleagues analyzed in injected some hard numbers into the debate on the effectiveness of universal testing.
They conducted a retrospective analysis of 358,086 Northern California infants 35 weeks and older who weighed at least 4 lbs, 7 oz and were born between January 1, 1995, and June 30, 2007.
They obtained records on demographics, bilirubin levels and inpatient phototherapy for the infants from existing databases.
Of the 358,086 infants included in the study, only two developed kernicterus, leading the authors to conclude that it was difficult to address the question of whether or not universal screening reduces the incidence of this condition.
They did find that universal screening led to more children being treated with phototherapy who did not actually need it, according to AAP guidelines.
"With additional education, the reduction in serious hyperbilirubinemia with universal bilirubin screening may be achieved without excessive phototherapy use," they wrote.