Factors Associated With Sudden Unexpected Postnatal Collapse.

Background: Sudden unexpected postnatal collapse (SUPC) is a category of sudden unexpected infant death (SUID), limited to previously well infants born at ≥34 weeks' gestation who die suddenly and unexpectedly at ≤6 days of age. We compared SUPC risk factors to SUID at older ages.

Methods: We conducted a retrospective cross-sectional study of 2010-2020 SUID deaths in the National Fatality Review Case Reporting System, excluding SUPC occurring in the birth hospital. Our main outcome was age at death: ≤6 days (SUPC) versus occurring from 7 days old but not having reached their first birthday. We performed multivariable logistic regression using stepwise selection.

Results: Of 6051 SUID deaths, 98 (1.6%) were SUPC. The median SUPC age was 4 days. A higher percentage of SUPC deaths occurred with surface sharing (73.5% versus 59.6%; odds ratio, 2.74 [1.59-4.73]). Infants who died of SUPC had higher odds of a mother ≥40 years (adjusted odds ratio [aOR], 13.1 [95% confidence interval [CI], 3.3-51.4]), being the first live birth (aOR, 4.0 [95% CI, 2.4-6.9]), being swaddled (aOR, 2.7 [95% CI, 1.7-4.1]), and of dying after their caregiver fell asleep while feeding (aOR, 2.6 [95% CI, 1.6-4.4]).

Conclusions: Common SUID risk factors, including surface sharing and prone position, were present in SUPC deaths. However, compared with SUID at older ages, SUPC was associated with older and primiparous mothers, swaddling, and the caregiver falling asleep while feeding the infant. Clinicians should reinforce all American Academy of Pediatrics' safe sleep recommendations and provide guidance regarding situations when parents may fall asleep during a feeding.