Objective: To evaluate serum levels of biomarkers as early indicators of onset of preeclampsia during pregnancy. Method: A nested case-control study was conducted among the pregnant women who visited for antenatal checkup at R.L. Jalappa Research Center, Kolar between August 2017 and May 2018. Serum levels of placental protein 13 (PP13), asymmetric dimethylarginine (ADMA), nitric oxide and caspase-3 which represents placentation and endothelial function were measured and compared between trimesters. Results and Discussion: There were 86 pregnant women enrolled at first trimester, the baseline values of women who developed preeclampsia were PP13 (477.54 ± 62.72 pg/ml), ADMA (21.06 ± 19.42 ng/ml), nitric oxide (3.71 ± 2.76 nmol/μL) and caspase-3 (6.15 ± 0.55 ng/ml). In the second trimester on follow up, the mean serum concentration of PP13 was 530.64 ± 69.10 pg/ml in preeclampsia versus 518.26 ± 49.33 pg/ml in normal pregnancy. The mean serum concentration of ADMA was 73.43 ± 30.95 ng/ml and nitric oxide 4.10 ± 2.70 nmol/μL in preeclampsia versus 21.06 ± 19.42 ng/ml and 4.85 ± 2.19 nmol/μL in normal pregnancy. The mean serum concentration of caspase-3 in preeclampsia was 22.65 ± 0.91 ng/ml versus normal pregnancy 18.45 ± 2.62 ng/ml were recorded. In preeclampsia, PP13 was positively correlated with nitric oxide and negatively correlated with ADMA. Conclusion: Decreased PP13, nitric oxide and elevated ADMA in first trimester and increased PP13, ADMA and decreased nitric oxide at second trimester reflects altered placentation and endothelial function.