Sudden unexpected postnatal collapse during the first week of life is rare but can have deleterious consequenses. A new study from Karolinska Institutet shows that the condition is more common than previously estimated and highlights measures that may reduce the risk.
Sudden unexpected postnatal collapse (SUPC) occurs when an apparently healthy newborn suddenly stops breathing and collapses during the first week of life. In a new study, published in the journal Acta Paediatrica, researchers investigated how common the condition is and when it occurs.
The researchers analysed approximately 483,000 births at seven maternity units in Stockholm between 2002 and 2022 and identified 149 cases of SUPC. This corresponds to 31 cases per 100,000 live births.
"It is important to remember that this is a very rare condition. According to our findings, it affects around 30 infants each year in Sweden, and two to four of these cases lead to death. Most cases occur during the infant's first day of life," says the study's senior author, Eric Herlenius , paediatrician at Karolinska University Hospital and Professor of Paediatrics at the Department of Women's and Children's Health, Karolinska Institutet.
The study found that 81 per cent of collapses occurred during the first 24 hours after birth, with half taking place within four hours of delivery. Seven per cent of affected infants died and 26 per cent sustained permanent neurological injuries. Two-thirds of the cases occurred while the infant was sharing a bed with a parent.
"Skin-to-skin contact is important for newborn infants, but parents need to ensure that the baby's airways are always clear and visible. Adults should not fall asleep while holding their baby skin to skin, and infants should not sleep in the same bed as their parents during the first three months of life," says Eric Herlenius
The researchers point out that SUPC still lacks a specific diagnostic code, making the condition difficult to monitor. According to the researchers, this may have contributed to an underestimation of its true incidence.
Reviewed medical records
To identify cases, the researchers reviewed electronic medical records of infants born after at least 35 weeks of pregnancy. The records were searched for symptoms suggestive of collapse, such as episodes of apnoea, bluish skin discolouration, or sudden loss of muscle tone. Each suspected case was then assessed according to internationally established criteria for SUPC.
Since 2011, the researchers have also collected urine samples from affected infants and compared them with samples from healthy infants of the same age. They found higher levels of a prostaglandin E2 metabolite in infants who experienced SUPC during the first days of life, the same period during which most collapses occurred
"We believe that clearer guidelines for safe skin-to-skin care and safe sleep environments are needed and could help reduce the number of cases further," says Eric Herlenius.
At the same time, the researchers aim to improve understanding of the biological mechanisms underlying the condition, including the elevated levels of prostaglandin E2 metabolite observed in some affected infants. By studying the relationship between these levels and the brainstem's control of breathing, the researchers hope to gain a better understanding of why some newborns develop SUPC and, in some cases, sudden unexpected death.
Swedish Research Council, the Swedish Brain Foundation, and Swedish government research funding provided to Region Stockholm (ALF funding) funded the research. The authors declare no conflicts of interest.
Publication
"Sudden unexpected postnatal collapse: A retrospective cohort study describing incidence, risk factors and role of perinatal transition", David Forsberg, Louise Steinhoff, Gustaf Drevin, Helena Idborg, Nicolas J. Pejovic, Eric Herlenius Acta Paediatrica, online 14 July 2026 doi: 10.1111/apa.70670
