Ultrasound Parameters of Umbilical Artery Blood Flow Are Associated with Amniotic Fluid and Umbilical Artery Concentrations of Erythropoietin and Oxidative Stress Injury

Abstract

Intrauterine hypoxia is the most frequent adverse intrauterine condition that occurs under a variety of circumstances including preeclampsia, placental insufficiency, high-altitude pregnancy, and any inflammatory condition during pregnancy resulting from gestational diabetes or even maternal obesity. However, early diagnosis of intrauterine hypoxia is still a challenge. In this study, we comparatively analyzed the systolic to diastolic ratio (S/D), resistant index (RI), and pulse index (PI) of the umbilical artery (UmA) and middle cerebral artery (MCA) blood flows obtained from 46 pregnant women with intrauterine hypoxia and 80 normal pregnant women at 28-31, 32-36, and 37-41 gestational weeks. Results found that the S/D, RI, and PI of UmA and MCA blood flows at 28-31, 32-36, and 37-41 gestational weeks were all increased in hypoxic fetuses than in normal fetuses ( $P<0.05$ ). The malondialdehyde (MDA) level was elevated but superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities were reduced in the UmA blood of pregnant women with intrauterine hypoxia compared with normal pregnant women ( $P<0.05$ ). It was found that the NADPH oxidase 2 (Nox2) and NADPH oxidase 4 (Nox4) activities were increased in the UmA blood of pregnant women with intrauterine hypoxia compared with normal pregnant women ( $P<0.05$ ). Results of ELISA methods showed that the expression level of survivin was lower but the expression levels of caspase-3, caspase-6, and caspase-9 were higher in the placental tissues of pregnant women with intrauterine hypoxia than those in normal pregnant women ( $P<0.05$ ). The concentrations of erythropoietin in the amniotic fluid and UmA blood were increased in pregnant women with intrauterine hypoxia compared with normal pregnant women ( $P<0.05$ ). The Spearman correlation analysis showed that the S/D, RI, and PI of UmA blood flow at 37-41 gestational weeks were positively correlated with the levels of Nox2, Nox4, and MAD and the UmA concentration of erythropoietin but negatively correlated with the activities of SOD, GSH-Px, and CAT ( $P<0.05$ ). In summary, the study indicates that ultrasound parameters of the UmA blood flow including S/D, RI, and PI could serve as predictors of intrauterine hypoxia.