Strangulation and suffocation deaths appear most common in infants 3 months old and younger, with most deaths occurring at 1 month of age. And they occur more often from Sunday through Wednesday than during the second half of the week.
"It seems that medical examiners or coroners seem to be moving away from SIDS as a diagnosis and more likely to report suffocation as the cause of death," said Shapiro-Mendoza. "We don't know the exact reason. It could have to do with better death investigation or stricter adherence to SIDS definition."
National death-scene guidelines for sudden, unexpected infant deaths were released in 1996, intended to standardize investigations and make them more user-friendly.
"One of the caveats here is: Was there truly an increase, or is there a more careful assessment of unexpected infant death cases?" Dewitt asked. "It's hard to know."
According to Dr. Cheryl Cipriani, an associate professor of pediatrics at Texas A&M Health Science Center College of Medicine and director of the Neonatal Intensive Care Unit at Scott & White hospital, as people have gotten better at identifying causes of death, some deaths that once were simply unexplained might now be attributed to accidental suffocation or strangulation rather than SIDS.
And, she said, the way SIDS has been defined has changed: If one component of the examination or investigation is missing, the death cannot be categorized definitively as "unexplained."
The authors of the study called for a more standardized nationwide system of investigating and classifying infant deaths in the United States as one means of furthering prevention efforts.
The American Academy of Pediatrics has more on infant safety.
SOURCES: Carrie K. Shapiro-Mendoza, Ph.D., epidemiologist, division of reproductive health, U.S. Centers for Disease Control and Prevention, Atlanta; Thomas G. DeWitt, M.D., director, division of general and community pediatrics, Cincinnati Children's Hospital Medical Center; Cheryl Cipriani, M.D., associate professor, pediatrics, Texas A&M Health Science Center College of Medicine, and director, Neonatal Intensive Care Unit, Scott & White, Temple, Texas; February 2009 Pediatrics