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 check-up 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.