text: Factors affecting materno-fetal transfer of iron in the rat.
  Materno-fetal transfer of iron was studied in the rat under various conditions affecting maternal iron kinetics. A low maternal plasma iron turnover rate (PITR), whether due to a low serum iron concentration or a reduced plasma volume, was associated with a decrease in the amount of iron transported to the fetuses. Conversely, a high PITR due to iron overload and a high serum iron concentration, produced a marked increase in the amount of iron received by the fetuses. No such increase was observed in fetuses of mothers made anemic by bleeding or phenylhydrazine, in whom both the PITR and erythropoietic activity were increased, persumably due to maternal competition for iron. The amount of iron crossing to the fetuses, therefore, is affected by the interplay of two conflicting factors: the PITR and maternal needs for iron, as dictated by the level of erythropoietic activity.