Birth Time and Early Outcomes in Very Preterm Infants in China: A Cohort Study

Background Previous studies suggest that birth timing may impact the prognosis of extremely premature infants, increasing early mortality and the risk of intensive resuscitation, asphyxia, or sIVH. The aim of this study was to investigate the relationship between birth timing and outcomes of very preterm infants (VPIs) in China. Methods This multicenter retrospective study used CHNN 2019–2021 data on preterm infants born at 24 ⁰ to 31 ⁶ weeks’ GA. Exposure included birth timing (daytime, evening, night) on weekdays and non-weekdays. The primary outcome was in-hospital mortality rate. Secondary outcomes included delivery room outcomes and morbidities. Results The study included 17,670 VPIs and found increased mortality during both daytime-evening shifts and night shifts on weekdays, primarily affecting infants born at 24 ⁰ to 27 ⁶ weeks’ GA. Among weekday births, evening shifts were associated with 5-minute Apgar scores ≤7 (aOR 1.22, 95% CI 1.07–1.39) and sIVH (aOR 1.30, 95% CI 1.08–1.57), while nighttime shifts were linked to hypothermia (aOR 1.13, 95% CI 1.02–1.24). In infants born at 28 ⁰ to 29 ⁶ weeks’ GA, night shifts were associated with intensive resuscitation (aOR 1.23, 95% CI 1.02–1.48), and evening shifts with 5-minute Apgar scores ≤7 (aOR 1.38, 95% CI 1.11–1.71). For infants born at 30 ⁰ to 31 ⁶ weeks’ GA, the evening shift significantly increased the risk of sIVH (aOR 1.78, 95% CI 1.27–2.48). Conclusion Mortality increased for infants born during daytime handovers and nighttime, especially at 24 ⁰ to 27 ⁶ weeks’ GA. Infants at 28 ⁰ to 31 ⁶ weeks’ GA faced higher risks of asphyxia, hypothermia, or sIVH during off-peak hours.