Researchers at U.C. San Francisco have found that newborns with an unusual pattern of metabolites in their blood — the byproducts created when the body processes energy — were far more likely to die from sudden infant death syndrome, adding to a growing body of research suggesting babies who die from SIDS may have underlying conditions that can be detected early in life.
The researchers compared the metabolic blood panels from the newborn heel prick tests of 354 infants born between 2005 and 2011 in California who died of SIDS, and compared them with the panels of healthy babies who were born at a similar gestational age and birth weight. They found that babies with unusual metabolites in their blood were 14 times more likely to die from SIDS as those with the lowest-risk pattern, according to the study published Monday in the journal JAMA Pediatrics.
“We were surprised the moment the data came out,” said senior author of the study Laura Jelliffe-Pawlowski, a professor at UCSF and New York University. “It suggests that the babies who pass away from SIDS may be having specific difficulties processing sugar and energy.”
Jelliffe-Pawlowski said this study alone is not enough to change clinical practice, or the state to begin identifying these unusual metabolite patterns in newborn heal prick samples, which are currently used to screen for 80 genetic and congenital disorders in California. But the findings are a promising contribution to scientists’ understanding of SIDS, the leading cause of death for infants between 1 month and 1 year of age, giving researchers an important new line of inquiry.
Much more research is needed, she said, including a study over time that identifies and monitors children with this unusual metabolic marker.
What causes SIDS?
For decades, scientists have been trying to figure out what causes SIDS, the sudden and unexplained death of an otherwise healthy infant before their first birthday. Ninety percent of SIDS deaths occur in babies ages 6 months or younger and peak between 2 and 4 months of age. The syndrome is also called “crib death,” because infants often die in their cribs.
In the 1980s, a major breakthrough was made linking SIDS with unsafe sleep practices, including putting a baby to sleep on their stomach, and public health agencies launched the first “safe sleep” campaigns in the 1990s, with public service announcements on TV and “Back to Sleep” messages printed on rice cereal boxes.
The campaigns were a success, and the recommendations are still given to parents around the world. The rate of SIDS plunged during the 1990s. But they plateaued around 1998 and have remained stubbornly high. In 2020, there were 3,400 sudden unexpected infant deaths in the United States, according to the Centers for Disease Control and Prevention, including babies who died from accidental suffocation or strangulation; nearly half, about 1,389, were classified as SIDS.
In the years since, researchers have come up with a number of underlying factors that might increase a baby’s risk of SIDS, including problems in the part of the brain that controls breathing, abnormal serotonin receptors and low levels of an enzyme connected to sleep arousal.
What does this study tell us?
There is likely no single cause for SIDS, but rather a variety of risk factors, including an underlying physical abnormality, premature birth and unsafe sleep conditions that can make an infant more vulnerable. The UCSF study provides evidence that problems in the way that a baby metabolizes glucose may also contribute to some cases.
Of particular importance is that these metabolic risk factors were able to be detected through the newborn heal prick screening that nearly every baby in the U.S. receives after birth. This means that babies who might be at heightened risk of SIDS could potentially be identified early and benefit from further testing, closer monitoring, and possibly interventions to try to prevent a tragedy.
“One of the holy grails of SIDS research is, is there something we could do at birth to identify babies who are at high risk for SIDS and then somehow intervene to prevent it,” said Dr. Thomas Keene, a pulmonologist at Children’s Hospital Los Angeles. The problem, he said, is that many babies have the same metabolic profile identified in the study but never go on to die of SIDS. An ideal marker, he said, would be much more specific.
Without further research proving a connection with SIDS, not enough is known to consider changing clinical practice, said Dr. Richard Goldstein, who directs the Robert’s Program on Sudden Unexpected Death in Pediatrics at Boston Children’s Hospital-Harvard Medical School, and councils parents whose babies have died from SIDS. “You can’t tell someone that their child’s likely to die from some kind of unknown and mysterious cause, and think that’s not without tremendous burden.”
Scott Oltman, another UCSF researcher who worked on the study, said his hope is that identifying the underlying physiological causes of SIDS will help parents who have lost their children.
“If you’re a parent who’s in the unfortunate position where you’ve lost an infant due to SIDS, when you’re searching for answers, and you happen to come across research that shows more physiological connections rather than environmental connections, I think it can, to some degree, alleviate some of the feelings of guilt,” Oltman said.
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