© 2022Introduction: Considering that preeclampsia is characterized by oxidative stress, inflammation, and endothelial dysfunction, we hypothesized that preeclampsia and preeclampsia severity may affect the telomerase levels of the mother. Methods: This cross-sectional case control study comprised 86 participants who were separated into three groups as severe preeclampsia, non-severe preeclampsia, and healthy control group. Venous blood samples were obtained from pregnant women with severe preeclampsia just before delivery for biochemical analysis and to evaluate maternal serum telomerase levels. Since gestational age, maternal age and BMI would have an effect on maternal serum telomerase levels, serum samples were taken in the control group and non-severe preeclampsia group at similar gestational age during clinical visits in order to homogenize these parameters, and these patients were followed up. Telomerase levels in maternal serum were evaluated using the enzyme-linked immune-sorbent assay. Results: Maternal age, nulliparity, body mass index (kg/m2) at blood sampling day, ethnicity, smoking and history of caesarian section were statistically similar among the groups. The mean birth weight percentiles were the lowest in the severe preeclampsia group. Fetal growth restriction rates were significantly higher in the severe preeclampsia group than in the non-severe preeclampsia group. Gestational age at blood drawn was similar among groups. Neutrophil lymphocyte ratio, platelet lymphocyte ratio, mean platelet volume, red cell distribution width and white blood cell were statistically different among groups. The serum telomerase level was 1.137 ± 0.390 ng/mL in the severe preeclampsia group, 0.763 ± 0.390 ng/mL in the non-severe preeclampsia group, and 0.425 ± 0.160 ng/mL in the control group (p < .001). Discussion: This study indicated that maternal serum telomerase levels were significantly increased in both preeclampsia groups.