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Mortality declined among extremely premature infants
The rates of overall mortality decreased among extremely premature infants from 2000 through 2011, specifically infant deaths ascribed to bronchopulmonary dysplasia and respiratory distress syndrome or deaths complicated by infection or central nervous system injury.
“Approximately one in four extremely premature infants born at 22 to 28 weeks of gestation does not survive the birth hospitalization; mortality rates decrease with each additional week of completed gestation,” researcher Ravi M. Patel, MD, MSc, assistant professor of pediatrics at Emory University School of Medicine and Children’s Healthcare of Atlanta, and colleagues wrote. “Historically, most extremely premature infants died within a few days after birth.”
Ravi M. Patel
While previous studies have indicated that recent changes — including prenatal use of glucocorticoids and antibiotic agents, use of surfactants and ventilation strategies — may have lowered the risk for death among extremely premature infants, significant data are lacking.
To determine current causes and timing of death among extremely premature infants, the researchers prospectively analyzed data from 6,075 deaths among 22,248 live births, with gestational ages of 22 to 28 weeks, approximately 12 to 18 weeks before their expected due date.
Infants were followed from birth to age 120 days, death, hospital discharge or relocation to another center. Infants who remained hospitalized for more than 120 days were evaluated for death until they were aged 1 year. The researchers then compared overall and cause-specific mortality across three periods: 2000-2003, 2004-2007 and 2008-2011.
The researchers observed a relative decrease of 9.6% per 1,000 live births in the overall mortality among extremely premature infants between 2004 and 2011, 53% of which was attributed to reductions in mortality due to respiratory distress syndrome and bronchopulmonary dysplasia.
The investigators also observed, however, an increase in premature infant deaths associated with necrotizing enterocolitis, which offset the overall mortality reduction by 26%. Researchers said that from 15 to 60 days after birth, necrotizing enterocolitis was the most common cause of premature infant death; bronchopulmonary dysplasia was identified as the leading cause of death beyond 60 days.
“The increase in mortality attributed to necrotizing enterocolitis may be related to improvements in the early survival of infants who would have otherwise died before they reached the typical postnatal age at which necrotizing enterocolitis occurs,” Patel and colleagues wrote.
In addition, within the examined time period, researchers found that infant mortality within 12 hours of birth was most commonly associated with immaturity, while mortality beyond 12 hours was frequently associated with respiratory distress syndrome.
“By understanding the causes and timing of death in premature infants, we can make more informed decisions as clinicians, better counsel families, and conduct more in-depth research to continue improving survival and long-term health of premature infants,” Patel said in a press release.
Disclosure: The researchers report no relevant financial disclosures.
