Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA.
Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
Am J Clin Nutr. 2022 Apr 1;115(4):1069-1079. doi: 10.1093/ajcn/nqac020.
During pregnancy iron can be obtained from the diet, body iron stores, or iron released from RBC catabolism. Little is known about the relative use of these sources to support fetal iron acquisition.
To describe longitudinal change in iron absorption and enrichment across gestation and partitioning of RBC iron to the fetus.
Fifteen pregnant women ingested an oral stable iron isotope (57Fe) in the second trimester (T2) of pregnancy (weeks 14-16) to label the RBC pool, and a second oral stable isotope (58Fe) in the third trimester (T3) (weeks 32-35). Absorption was measured at T2 and T3. Change in RBC 57Fe enrichment was monitored (18.8-26.6 wk) to quantify net iron loss from this pool. Iron transfer to the fetus was determined based on RBC 57Fe and 58Fe enrichment in umbilical cord blood at delivery.
Iron absorption averaged 9% at T2 and increased significantly to 20% (P = 0.01) by T3. The net increase in iron absorption from T2 to T3 was strongly associated with net loss in maternal total body iron (TBI) from T2 to T3 (P = 0.01). Mean time for the labeled RBC 57Fe turnover based on change in RBC enrichment was 94.9 d (95% CI: 43.5, 207.1 d), and a greater decrease in RBC 57Fe enrichment was associated with higher iron absorption in T2 (P = 0.001). Women with a greater decrease in RBC 57Fe enrichment transferred more RBC-derived iron to their fetus (P < 0.05).
Iron absorption doubled from T2 to T3 as maternal TBI declined. Women with low TBI had a greater decrease in RBC iron enrichment and transferred more RBC-derived iron to their neonate. These findings suggest maternal RBC iron serves as a significant source of iron for the fetus, particularly in women with depleted body iron stores.
怀孕期间铁可来自于饮食、体内铁储存或红细胞分解代谢释放的铁。对于这些来源相对用于支持胎儿铁获取的情况知之甚少。
描述妊娠期间铁吸收和富集的纵向变化以及红细胞铁向胎儿的分配。
15 名孕妇在妊娠中期（T2）（14-16 周）口服稳定的铁同位素（57Fe）标记红细胞池，并在妊娠晚期（T3）（32-35 周）口服第二口稳定同位素（58Fe）。在 T2 和 T3 时测量吸收情况。监测 RBC 57Fe 富集的变化（18.8-26.6 周）以量化从该池丢失的净铁量。根据分娩时脐带血中 RBC 57Fe 和 58Fe 富集确定铁向胎儿的转移。
T2 时铁吸收率平均为 9%，到 T3 时显著增加到 20%（P=0.01）。从 T2 到 T3 的铁吸收净增加与 T2 到 T3 的母体总铁量（TBI）净减少密切相关（P=0.01）。基于 RBC 富集变化的标记 RBC 57Fe 周转率的平均时间为 94.9 d（95%CI：43.5，207.1 d），RBC 57Fe 富集下降更大与 T2 时铁吸收更高相关（P=0.001）。RBC 57Fe 富集下降更大的女性向胎儿转移更多的 RBC 衍生铁（P<0.05）。
从 T2 到 T3，铁吸收增加了一倍，而母体 TBI 下降。TBI 较低的女性 RBC 铁富集下降更大，并向新生儿转移更多的 RBC 衍生铁。这些发现表明母体 RBC 铁是胎儿铁的重要来源，尤其是在体内铁储存耗尽的女性中。
