Background: Pregnancy is a physiological condition that affects the general and oral health.It is also associated with an increase in oxidative stress, which may presispose to oral diseases including dental caries. Aim of the study: This study aimed to measure salivary protein carbonyl, glutathione peroxidase and selenium levels of women who are pregnant and their association with dental caries in comparison to non-pregnant women, and to find out the mostly affected biomarker of oxidative stress during pregnancy. Subjects, materials and methods: A cross-sectional research was performed for a samples of 30 pregnant and 30 non-pregnant women who were chosen from city of Baghdad's Primary Healthcare Centers. Both groups aged 25-30 years. In unstimulated salivary samples protein carbonyl and glutathione peroxidase were determined colorimetrically using spectrophotometer by utilizing ready-made assay kits. Salivary selenium level was obtained by atomic absorption spectrophotometer. Plaque index had been used to determine the thickness of dental plaque. Caries was recorded using the Decayed, Missing, and Filled (DMF) index. described by WHO in 1997. Data was statistically analyzed using descriptive statistics method and Student's t-test, Wilcoxon sum rank test and Spearman’s correlation in addition to Receiver Operating Characteristics Curve (ROC test) (α=5%). Results: The plaque index and salivary protein carbonyl values were significantly higher among pregnant while salivary selenium and glutathione peroxidase recorded significantly lower levels among pregnant women. Dental caries parameters were higher among pregnant with significant difference for MS fraction only. ROC area for protein carbonyl equal one with highest sensitivity and specificity. Conclusion: Pregnant women recorded higher dental caries severity with higher salivary protein oxidation but lowers salivary antioxidant defense mechanisms. Salivary protein carbonyl is more ideal, valid and mostly affected biomarker in revealing the oxidative stress status during pregnancy