[Analysis of perinatal factors for death or severe intraventricular hemorrhage within the first week of life in preterm infants with gestational age <32 weeks].

<b>Objective:</b> To analyze the incidence and perinatal factors of death or severe intraventricular hemorrhage (sIVH) within the first week of life in preterm infants with gestational age <32 weeks. <b>Methods:</b> Based on the online data platform of Sina-northern Neonatal Network (SNN), a case-control study was conducted using clinical data from 8 903 preterm infants with gestational age <32 weeks admitted to 35 neonatal intensive care units (NICU) between 2019 and 2023. Infants were classified by gestational age at birth into very preterm infants and extremely preterm infants. Infants who died or developed sIVH within the first week of life were defined as the case group, while those who survived and did not develop sIVH were defined as the control group. The general information of the infants, maternal perinatal factors, the 5^th minute Apgar score, incidence of hypothermia or early-onset sepsis, and the first arterial blood pH value were compared between the case and control groups of very preterm infants and extremely preterm infants. The <i>χ²</i> test and Wilcoxon rank-sum test were used for intergroup comparisons. A multivariable logistic regression model nas used to analyze the factors for death or sIVH within the first week of life in very preterm and extremely preterm infants. <b>Results:</b> Among the 8 903 preterm infants with gestational age <32 weeks, 4 993 (56.1%) were male, with a gestational age at birth of 30.0 (28.4, 31.0) weeks. A total of 865 cases (9.7%) were death or sIVH within the first week of life. The case group took up 5.8% (426/7 316) and 27.7% (439/1 587) of very preterm infants and extremely preterm infants, respectively. Compared to the control group, the case group of very preterm and extremely preterm infants both had higher incidences of low gestational age, low birth weight, small for gestational age, the 5^th minute Apgar score ≤7, early-onset sepsis, hypothermia at admission, and first arterial blood pH <7.20 (all <i>P</i><0.001). The proportion of mother's full course antenatal corticosteroids use were both lower in both case group (both <i>P</i><0.001). Multivariate Logistic regression analysis revealed several risk factors for death or sIVH within the first week of life in very preterm and extremely preterm infants, including: low gestational age (<i>OR</i>=0.70 and 0.74, 95%<i>CI</i> 0.60-0.82 and 0.66-0.83, both <i>P</i><0.001), low birth weight (<i>OR</i>=0.99 and 0.99, 95%<i>CI</i> 0.99-1.00 and 0.99-1.00, both <i>P</i><0.05), early-onset sepsis (<i>OR</i>=1.82 and 2.20, 95%<i>CI</i> 1.42-2.34 and 1.74-2.79, both <i>P</i><0.001), the 5^th minute Apgar score ≤7 (<i>OR</i>=1.41 and 2.69, 95%<i>CI</i> 1.10-1.81 and 2.17-3.34, both <i>P</i><0.01), hypothermia at admission (<i>OR</i>=1.55 and 1.38,95%<i>CI</i> 1.17-2.07 and 1.08-1.76,both <i>P</i><0.05) and the first arterial blood pH <7.20 (<i>OR</i>=2.20 and 2.57, 95%<i>CI</i> 1.70-2.84 and 2.05-3.21, both <i>P</i><0.001). Multiple births were an independent risk factor only for extremely preterm infants (<i>OR</i>=1.32, 95%<i>CI</i> 1.02-1.71, <i>P</i><0.05). Prenatal administration of a full course of antenatal corticosteroids was identified as a protective factor in very preterm and extremely preterm infants (<i>OR</i>=0.74 and 0.62, 95%<i>CI</i> 0.58-0.95 and 0.51-0.76, both <i>P</i><0.05). <b>Conclusions:</b> The incidence of death or sIVH within the first week of life remains high in preterm infants with gestational age <32 weeks. The smaller gestational age and lower birth weight, early-onset sepsis, birth asphyxia, hypothermia at admission, and a first arterial blood pH <7.20 were independent risk factors for death or sIVH within the first week of life in preterm infants with gestational age <32 weeks. A full course of antenatal corticosteroids significantly reduced the risk of these adverse outcomes.