This study will explore the methylation pattern of the Catechol-O-methyltransferase gene to determine its role in the pathogenesis of preeclampsia, association of Val158Met polymorphism with a wide range of oxidative stress biomarkers, major antioxidants vitamins, and blood pressure regulating amines in preeclamptic Pakistani women.<h4>Methods and analysis</h4>In this prospective case-control study, 85 preeclamptic and 85 normotensive pregnant women will be recruited in their third trimesters. This evidence concerns the gene COMT and preeclampsia.