Effect of iron stores and hysterectomy on iron absorption and distribution in pregnant mice.

Intestinal uptake (U) and transport (T) of 50Fe from a 1-mug oral dose was studied in the mouse. U increased to a similar degree in both pregnant and iron-deficient animals. The increase in T was greater in pregnant than in iron-deficient mice. In iron-loaded pregnant mice, U increased to levels found in pregnant animals, whereas T increased, but by a lesser amount. Termination of pregnancy by delivery or hysterectomy at days 20-21 resulted in a fall in U and T to normal levels within 24 h. Eighty percent of iron transported across the intestine in pregnancy was recovered from the fetuses, compared to 6.7% recovered in the maternal liver. Hepatic uptake was lower in pregnant than in iron-deficient mice or in postpartum mice with persisting iron deficiency. Hepatic uptake by the maternal liver after an intravenous dose of 2 mug 50Fe increased to levels in iron-deficient mice within 5 min of hysterectomy. The results demonstrate an effect of pregnancy on intestinal iron transport and its distribution that was dependent on the presence of fetuses and placentas.