An ovine model of maternal iron poisoning in pregnancy

An ovine model of maternal iron poisoning in pregnancy was used to examine the placental transport of deferoxamine and ferrioxamine and to follow maternal and fetal serum iron concentrations when maternal serum iron levels exceeded total iron-binding capacity. Ewes in the third stage of gestation underwent hysterotomy and delivery of the fetal head through an abdominal incision while under ketamine and halothane anesthesia. The fetal external jugular vein was catheterized for sampling of venous blood while the fetus remained in utero. Administration of deferoxamine mesylate or ferrioxamine mesylate IV to ewes was not accompanied by measurable deferoxamine or ferrioxamine in fetal blood. In a final experiment, four gravid ewes in a control group received 2 mg/kg maternal body wt iron IV over 60 minutes. An experimental group comprising another four ewes received similar doses of iron but then received 50 mg/kg deferoxamine mesylate IV over 15 minutes. Control and deferoxamine ewes reached similar peak maternal serum iron concentrations (2,479 ± 266 and 2,121 ± 343 μg/dL, respectively). The markedly elevated maternal serum iron concentrations were not accompanied by meaningful elevations in fetal serum iron levels over baseline values. Maternal deferoxamine infusion resulted in a more rapid fall in maternal serum iron concentrations but had no effect on fetal serum iron levels. The ovine fetus appears to be protected from elevated maternal serum iron concentrations in the last trimester of pregnancy. It could not be demonstrated that meaningful quantities of deferoxamine or ferrioxamine cross the placenta in the last trimester. These data are in keeping with limited experience in human beings and suggest that deferoxamine can be administered to a woman suffering from significant iron poisoning without concern for producing adverse fetal effects.