FETAL HYPOXIA AS A CAUSE OF UNVAFOURABLE PREGNANCY OUTCOMES: A SYSTEMATIC REVIEW OF ASSESSMENT METHODS

Abstract

Hypoxia is one of the most frequent and serious types of stress for the human body. Hypoxia during pregnancy has adverse effects on fetal that may have implications not only for antenatal, but also postnatal period and even adulthood. Hypoxia usually occurs due to the placental insufficiency - a process in which there is a progressive decrease of the placental functions, when the transfer of oxygen and nutrients to the fetus through the placenta decreases, which leads to hypoxia and acidosis. Subsequent fetal hypoxemia stimulates the suppression of metabolic responses to preserve available nutrients, resulting in fetal growth restriction. This article presents an overview of modern scientific literature considering an etiology and pathophysiology of fetal hypoxia. Special attention is paid on the methods of evaluating fetal hypoxia in obstetric practice, such as Doppler, measuring lactate from fetal scalp blood testing, CTG monitoring, detection of RNA caused by hypoxia in maternal blood, measurement of the pH of the umbilical cord vessels, ECG-STan, fetal pulsoximetry. A new parameter for assessing the condition of the fetus, called the "non-reassuring fetal status" was observed, and the diagnostic criteria were described thoroughly. This systematic review presents a qualitative analysis of diagnostic methods and predictors of the outcome of pregnancies with acute and progressive fetal hypoxia. The study includes full-text publications in Russian and English on the methods of assessing the state of fetal hypoxia during pregnancy and childbirth, as well as their validity. In total, 548 sources were identified in PubMed, SCOPUS and eLIBRARY.RU databases. After screening, 53 articles were selected and included in the qualitative synthesis.