Supplementary Material for: Sudden unexpected postnatal collapse (SUPC) in the Netherlands: a national registry study.

Objective
Sudden unexpected postnatal collapse (SUPC) is a rare and potentially life-threatening event with variable reported incidences, mostly derived from in-hospital data. This study investigated the incidence, aetiology and circumstances of SUPC in the Netherlands, and assessed differences between in-hospital and home-settings.
Design
Data concerning SUPC-cases were obtained through a web-based registry managed by the Dutch Paediatric Surveillance Unit from April 2019 to April 2022.
Patients
SUPC was defined as a collapse within 24 hrs of birth requiring resuscitation with at least positive pressure ventilation in infants born at ≥ 35 weeks of gestation and with a 5-minute Apgar-score ≥ 8.
Results
Of 94 registered SUPC-cases, 60 met inclusion criteria; 52 cases occurred in hospital and 8 at home. The annual incidence ranged between 7 and 17 per 100,000 live births, with an average of 11 per 100,000. Median time to collapse was 64 minutes, with over two-thirds occurring within two hours of birth. Collapses occurring at home occurred significantly later than those in hospital (165 minutes vs. 60 minutes; p< 0.05) and were associated with substantially higher mortality rates (37.5% vs. 6%; p<0.05). Approximately half of all SUPC-cases involved possible or definite airway obstruction, which- compared with other aetiologies- was more often related to preventable factors like reduced maternal vigilance, and covering of the infant’s nose and mouth.
Conclusions. SUPC occurs in hospitals and at home, with later onset and higher mortality outside the hospital. Greater awareness and prevention are needed in both settings.