Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden.
Ann Nutr Metab. 2017;71 Suppl 3:16-23. doi: 10.1159/000480741. Epub 2017 Dec 22.
Low birth weight (LBW), defined as a birth weight of <2,500 g, affects 16% of all newborns and is a risk factor for impaired neurodevelopment as well as adverse cardiovascular and metabolic outcomes, including hypertension. LBW infants include both term, small for gestational age infants and preterm infants. Most LBW infants have only marginally LBW (2,000-2,500 g). Recent advances in neonatal care have significantly improved the survival of very LBW (VLBW) infants (<1,500 g). LBW infants are at high risk of iron deficiency due to low iron stores at birth and higher iron requirements due to rapid growth. Using a factorial approach, iron requirements of LBW infants have been estimated to be 1-2 mg/kg/day, which is much higher than the requirements of term, normal birth weight infants, who need almost no dietary iron during the first 6 months of life. In VLBW infants, blood losses and blood transfusions related to neonatal intensive care, as well as erythropoietin treatment, will greatly influence iron status and iron requirements. The timing of umbilical cord clamping at birth is of great importance for the amount of blood transfused from the placenta to the newborn and thereby total body iron. Delayed cord clamping of LBW infants is associated with less need for blood transfusion, less intraventricular hemorrhage, and less necrotizing enterocolitis. Randomized controlled trials have shown that an iron intake of 1-3 mg/kg/day (1-2 mg for marginally LBW and 2-3 mg for VLBW) is needed to effectively prevent iron deficiency. There is some recent evidence that these levels of iron intake will prevent some of the negative health consequences associated with LBW, especially behavioral problems and other neurodevelopmental outcomes and possibly even hypertension. However, it is also important to avoid excessive iron intakes which have been associated with adverse effects in LBW infants.
低出生体重（LBW）定义为出生体重<2500 克，影响所有新生儿的 16%，是神经发育受损以及不良心血管和代谢结局的危险因素，包括高血压。LBW 婴儿包括足月、小于胎龄儿和早产儿。大多数 LBW 婴儿只有轻微 LBW（2000-2500 克）。最近新生儿护理的进步显著提高了极低出生体重（VLBW）婴儿（<1500 克）的存活率。LBW 婴儿由于出生时铁储存量低，以及由于快速生长而需要更高的铁需求，因此存在缺铁的高风险。使用因子分析方法，估计 LBW 婴儿的铁需求量为 1-2 毫克/公斤/天，远高于足月、正常出生体重婴儿的需求量，后者在生命的头 6 个月几乎不需要膳食铁。在 VLBW 婴儿中，与新生儿重症监护相关的血液流失和输血，以及促红细胞生成素治疗，将极大地影响铁状态和铁需求。出生时脐带夹闭的时间对于从胎盘向新生儿输送的血液量以及总铁量非常重要。延迟 LBW 婴儿的脐带夹闭与减少输血、减少脑室周围出血和坏死性小肠结肠炎的需求相关。随机对照试验表明，需要 1-3 毫克/公斤/天的铁摄入量（1-2 毫克用于轻微 LBW，2-3 毫克用于 VLBW），以有效预防缺铁。最近有一些证据表明，这些铁摄入量水平将预防与 LBW 相关的一些负面健康后果，特别是行为问题和其他神经发育结局，甚至可能预防高血压。然而，避免过量摄入铁也很重要，过量摄入铁与 LBW 婴儿的不良影响有关。
