胎儿和新生儿的免疫系统尚未发育成熟,IgG可以通过胎盘由母体主动转运至胎儿体内,胎儿循环中的IgG几乎全部来自母体。在孕期最后一个月,胎儿循环中的IgG接近10g/L,并在足月时超过母体,但早产儿IgG浓度仅为5g/L。在美国食品与药品管理局(FDA)批准的静脉免疫球蛋白(IVIG)适应证仅 Fetal and neonatal immune system has not yet mature, IgG can be transported from the mother to the fetus through the placenta, the fetus in the fetus almost all of the IgG from the mother. During the last months of pregnancy, IgG in the fetal circulation is approaching 10 g / L and exceeds maternal in term, but preterm infant IgG concentration is only 5 g / L. In the United States Food and Drug Administration (FDA) approved intravenous immunoglobulin (IVIG) indications only