Supplementary Material for: Early-Pregnancy Circulating Antioxidant Capacity and Hemodynamic Adaptation in Recurrent Placental Syndrome: An Exploratory Study

Background/Aims: Placental syndromes (PS) refer to pregnancy complications that include gestational hypertension, (pre)eclampsia, HELLP syndrome, and/or placental insufficiency-induced fetal growth restriction. These disorders are characterized by increased oxidative stress. This study aims to test the hypothesis that the abnormal hemodynamic adaptation to pregnancy, typical for early PS pregnancy, is accompanied by abnormal maternal levels of antioxidants relative to those in normal pregnancy. Methods: Before, and at 12, 16, and 20 weeks pregnancy, we measured trolox equivalent antioxidant capacity (TEAC), uric acid (UA), and TEACC (TEAC corrected for UA) in maternal serum of former PS patients, who either developed recurrent PS (rPS; n = 16) or had a normal next pregnancy (non-rPS; n = 23). Concomitantly, we also measured various hemodynamic variables. Results: rPS differed from non-rPS by higher TEACC levels before pregnancy (178 vs. 152 µM; p = 0.02) and at 20 weeks pregnancy (180 vs. 160 µM; p = 0.04). Only non-rPS responded to pregnancy by significant rises in hemodynamic measures. Conclusion: These data indicate that rPS pregnancies are preceded by an increase in antioxidant capacity, presumably induced by subclinical vascular injury and low-grade chronic inflammation.