Suggestion of an active transport of iron to the fetus in human pregnancy and its dependence on maternal serum iron levels

The present findings suggest the possible involvement of an active mechanism for transport of iron to the fetus. In all the 19 subjects studied, the cord serum iron levels tended to be higher (129.2 ± 56.8 ug/100ml) than the maternal serum iron levels (74.0 ± 35.9 ug/100ml) at parturition even in maternal iron deficiency. The significant difference (P< 0.001) between cord serum iron levels and the maternal iron levels shows that an active transport mechanism working against a gradient in favour of the fetus exists. The availability of iron to the fetus appears to be dependent on maternal serum iron levels but not on maternal iron stores. This finding serves to stress the importance of iron supplements in pregnancy. A hypothetical model for iron transfer from maternal circulation to fetal circulation is described.