EFFECTS OF CHRONIC MATERNAL ANEMIA ON SYSTEMIC AND UTEROPLACENTAL OXYGENATION IN NEAR-TERM PREGNANT SHEEP

OBJECTIVE: The hypothesis of our study was that both the systemic and uteroplacental circulations would adapt to chronic maternal anemia to ensure that oxygen supply to maternal tissues would be adequate. STUDY DESIGN: We measured cardiac output and uteroplacental blood flow and calculated systemic and uteroplacental oxygen delivery, extraction, and consumption in pregnant sheep that were anemic for 6 days (hematocrit 14%) and in normal sheep (hematocrit 28%). RESULTS: When compared with normal pregnant sheep, anemic pregnant sheep had increases in cardiac output and uteroplacental blood flow, neither of which was sufficient to prevent systemic or uteroplacental oxygen delivery from decreasing. In spite of decreases in oxygen delivery, systemic and uteroplacental oxygen consumptions were maintained at normal levels because of increases in oxygen extraction. CONCLUSION: Maternal systemic and uteroplacental circulations are capable of adapting well to chronic maternal anemia.