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 pO(2) and A-V pCO(2) differences compared to non-pre-eclampsia (A-V pO(2), 7.1+/-3.8 mm Hg vs. 11.3+/-5.9 mm Hg, P=0.001; A-V pCO(2), 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 pO(2) and A-V pCO(2) differences compared to non-pre-eclampsia (A-V pO(2), 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 pO(2) but not arterial pO(2) (Venous pO(2), 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.