Objective(s): Angiogenesis is one of the important events of pregnancy. The aim of this study was to investigate the changes serum levels of angiogenic (vascular endothelial growth factor, VEGF) and anti-angiogenic (endostatin and solubleVEGFR) factors according to trimesters in pregnant women. Furthermore, we aimed at investigating the possible predictive value of serum VEGF, endostatin and serum sVEGFR in pregnancy. \nMaterials and Methods: This longitudinal cohort study included healthy pregnant (n=30) and non-pregnant women (n=30) admitted to Sivas Primary Health Care Center. Venous blood samples (3 ml) were collected from each pregnant women for each trimester (first trimester 12 and 13 weeks of pregnancy, second trimester 26 and 27 weeks of pregnancy and third trimester 34 to 38 weeks of pregnancy). Maternal serum concentrations of VEGF, sVEGFR-1 and endostatin were determined by sensitive and specific immunoassays (R&D Systems, Minneapolis, MN, USA). All immunoassays utilized a sandwich enzyme immunoassay technique. \nResults: Serum VEGF concentrations were significantly higher compared to the control in the first and second trimester of pregnancy (p<0.01). In addition, the serum levels of endostatin and sVEGFR were significantly lower compared to the control in the same trimester (p<0.01). A negative correlation was found between the expression of VEGF with endostatin and sVEGFR (r= -0.409, p<0.001). \nConclusion: In conclusion, serum VEGF concentrations are higher in the first trimester compared to third, while plasma endostatin and sVEGFR concentrations are lower. In the light of this information, these factors can be used as predictive factors in pregnancy.