Oronasal blood, intrathoracic petechiae and pulmonary hemorrhages differentiate prone separate-bed from bed-sharing SIDS cases

PURPOSE: To compare autopsy findings in sudden infant death syndrome (SIDS) cases found prone in a separate bed with those occurring during bed-sharing, and to contrast these with confirmed asphyxia and violent death controls. METHODS: We conducted a retrospective review of 313 SIDS cases from Southeast Norway (1984-2021) to assess forensic autopsy findings and death scene circumstances. A subset of cases was selected for blinded re-evaluation, with standardized microscopic examination of lung sections and semi-quantitative scoring of intra-alveolar hemorrhage. RESULTS: As SIDS incidence declined, the proportion of bed-sharing cases increased from 7% in the 1980s to 52% after 2010 (p < 0.001). Bed-sharing SIDS infants were younger, more often found supine, and more frequently had oronasal blood and intra-alveolar hemorrhage reported. Separate-bed SIDS infants were predominantly found prone and more often exhibited petechiae on the surfaces of the thymus, lungs and heart. In the re-evaluated cohort, mean intra-alveolar hemorrhage scores were highest in bed-sharing SIDS (3.0 on a 0-4 scale) compared with prone SIDS (1.1), strangulation (1.2), and violent deaths (1.6) (all p ≤ 0.01). Scores did not differ significantly between bed-sharing SIDS and suffocation (2.3). Intra-alveolar hemorrhage was not linked to cardiopulmonary resuscitation. CONCLUSION: Pulmonary and intrathoracic findings in SIDS vary with sleep environment. Bed-sharing SIDS is associated with more severe intra-alveolar hemorrhage, whereas prone separate-bed SIDS more often shows intrathoracic petechiae. These findings suggest that bed-sharing-related and prone-related SIDS represent distinct pathological patterns with different underlying causes and death mechanisms, although both conditions remain unexplained.