Supplementary Material for: Neonatal Hemoglobin Levels in Preterm Infants Are Associated with Early Neurological Functioning

<b><i>Background:</i></b> Neonatal anemia may compromise oxygen transport to the brain. The effects of anemia and cerebral oxygenation on neurological functioning in the early neonatal period are largely unknown. <b><i>Objective:</i></b> This study aimed to determine the association between initial hemoglobin levels (Hb) and early neurological functioning in preterm infants by assessing their general movements (GMs). <b><i>Methods:</i></b> A retrospective analysis of prospectively collected data on preterm infants born before 32 weeks of gestation was conducted. We excluded infants with intraventricular hemorrhage &gt; grade II. On day 8, we assessed infants’ GMs, both generally as normal/abnormal and in detail using the general movement optimality score (GMOS). We measured cerebral tissue oxygen saturation (r_cSO₂) on day 1 using near-infrared spectroscopy. <b><i>Results:</i></b> We included 65 infants (median gestational age 29.9 weeks [IQR 28.2–31.0]; median birth weight 1,180 g [IQR 930–1,400]). Median Hb on day 1 was 10.3 mmol/L (range 4.2–13.7). Lower Hb on day 1 was associated with a higher risk of abnormal GMs (OR = 2.3, 95% CI: 1.3–4.1) and poorer GMOSs (<i>B</i> = 0.9, 95% CI: 0.2–1.7). Hemoglobin strongly correlated with r_cSO₂ (rho = 0.62, <i>p</i> &lt; 0.01). Infants with lower r_cSO₂ values tended to have a higher risk of abnormal GMs (<i>p</i> = 0.06). After adjusting for confounders, Hb on day 1 explained 44% of the variance of normal/abnormal GMs and r_cSO₂ explained 17%. Regarding the explained variance of the GMOS, this was 25% and 16%, respectively. <b><i>Conclusions:</i></b> In preterm infants, low Hb on day 1 is associated with impaired neurological functioning on day 8, which is partly explained by low cerebral oxygenation.

**背景**：新生儿贫血可损害脑组织的氧输送能力，目前关于贫血与脑氧合状态在新生儿早期对神经功能的影响尚不清楚。**研究目的**：本研究通过评估早产儿的全身运动（general movements, GMs），旨在明确初始血红蛋白（hemoglobin, Hb）水平与早产儿早期神经功能之间的关联。**研究方法**：本研究对前瞻性收集的胎龄小于32周的早产儿数据开展回顾性分析，排除存在Ⅱ级以上颅内出血的患儿。于出生后第8天评估患儿的全身运动（general movements, GMs），既从整体层面将其划分为正常/异常，又采用全身运动优化评分（general movement optimality score, GMOS）进行详细量化评分。于出生后第1天采用近红外光谱技术检测患儿的脑组织氧饱和度（cerebral tissue oxygen saturation, r_cSO₂）。**研究结果**：本研究共纳入65例早产儿，其胎龄中位数为29.9周[四分位数间距（interquartile range, IQR）：28.2~31.0周]，出生体质量中位数为1180g[IQR：930~1400g]。患儿出生后第1天的Hb中位数为10.3mmol/L（范围：4.2~13.7mmol/L）。出生后第1天的Hb水平越低，患儿出现异常全身运动的风险越高（比值比（odds ratio, OR）=2.3，95%置信区间（confidence interval, CI）：1.3~4.1），且全身运动优化评分越低（回归系数（B）=0.9，95%CI：0.2~1.7）。Hb水平与r_cSO₂呈显著正相关（rho=0.62，P<0.01）。r_cSO₂水平较低的患儿，其异常全身运动的风险呈升高趋势（P=0.06）。校正混杂因素后，出生后第1天的Hb水平可解释正常/异常全身运动44%的变异度，r_cSO₂可解释17%的变异度；针对全身运动优化评分的解释变异度，则分别为25%和16%。**研究结论**：对于早产儿而言，出生后第1天的低Hb水平与出生后第8天的神经功能损害密切相关，这一关联部分可通过脑氧合水平低下得到解释。