Context Preeclampsia is a common pregnancy complication, posing significant risks to both the mother and fetus. Predicting and determining the risks of this disease is crucial. Aims This research aims to understand the pathogenetic role of several factors in the development and progression of preeclampsia, particularly in relation to its severity in pregnant patients. Methods The study included 60 pregnant women diagnosed with either mild or severe preeclampsia and 40 healthy pregnant women for comparison. Blood plasma was analysed using biochemical methods, and blood microcirculation parameters were determined to identify homeostatic abnormalities in early preeclampsia. Key results A molecular genetic study revealed the frequency of the endothelial nitric oxide gene eNOSC774T . Homeostatic abnormalities were statistically correlated with polymorphic genotypes of the eNOSC774T gene. Conclusions The research found a correlation between the T774T eNOS genotype mutation and the severity of preeclampsia, alongside significant homeostasis abnormalities in patients. Implications The T774T mutant genotype of the eNOS gene and higher levels of lipid peroxidation products are strongly linked to the severity and progression of preeclampsia. This highlights a significant connection between genetic predisposition and biochemical abnormalities in the disease's development.