Background: The pathophysiological mechanism underlying pregnancy complications is not entirely known. Although it is currently impossible to predict the occurrence of redox imbalance, it is possible to identify women with a high or medium risk of developing this disease prior to a negative outcome by non-invasive diagnostic methods. The Aim: This study aimed to examine the possible role of the parameter of oxidative stress (OS) measured in early pregnancy in the screening/treatment of obesity and its complications during pregnancy. Methods: This research was designed as a prospective observational cross-sectional clinical study which included 40 non-obese and 31 obese pregnant women between 11 and 13 g.w. who were managed in the Department of Obstetrics, University Clinical Center Kragujevac in Serbia. We collected anthropometric and clinical indicators, maternal and pregnancy factors, and measured prooxidative parameters from blood samples. Results: We observed significantly increased levels of the superoxide anion radical, hydrogen peroxide and the index of lipid peroxidation in the Obese group in comparison with the Non-Obese group and significantly decreased bioavailability of nitrites in the Obese group in comparison with the Non-Obese group. Conclusions: The determination of systemic parameters of OS in early pregnancy could be a good methodological approach in the screening/treatment of obesity during pregnancy and this approach should be followed for the screening of endothelial dysfunction in pregnancy which needs further monitoring and/or treatment.