Decreased placental oxygenation capacity in pre-eclampsia: clinical application of a novel index of placental function preformed at the time of delivery
Objective: We have previously described placental oxygenation capacity as an index of placental function. The aim of this study was to utilize this test to evaluate placental gas exchange capacity in pre-eclampsia and fetal growth restriction (FGR). Study design: Two nested case-control studies were conducted between: (i) pre-eclamptic appropriate-for-gestational-age fetus (AGA) and non-pre-eclamptic AGA; and (ii) pre-eclamptic FGR and non-pre-eclamptic FGR based on gestational age match. Umbilical A-V gas differences were compared between groups. Results: Pre-eclamptic AGA was associated with smaller A-V pO2 and A-V pCO2 differences compared to non-pre-eclampsia (A-V pO2, 7.1±3.8 mm Hg vs. 11.3±5.9 mm Hg, P=0.001; A-V pCO2, 7.8±5.7 mm Hg vs. 10.7± 5.9 mm Hg, P=0.01). Pre-eclamptic FGR was associated with smaller A-V pO2 and A-V pCO2 differences compared to non-pre-eclampsia (A-V pO2, 6.6±3.1 mm Hg vs. 10.8±8.1 mm Hg, P<0.001; 6.7±4.5 mm Hg vs. 10.9±10.3 mm Hg, P=0.044). Pre-eclamptic FGR also had significantly lower venous pO2 but not arterial pO2 (Venous pO2, 20.3±6.3 mm Hg vs. 25.4±11.9 mm Hg, P=0.003). Conclusion: Pre-eclampsia decreases the placental oxygenation capacity as measured by the umbilical arterial-venous oxygen difference.
