OBJECTIVE: Placenta previa is associated with the development of pregnancy complications such as pregnancy-induced hypertension, preeclampsia, intrauterine growth restriction, placental prolapse, and perinatal mortality. The aim of this study was to evaluate morphometric and immunohistochemical changes in the umbilical cord of placenta previa and normotensive patients. STUDY DESIGN: Pregnant patients with placenta previa and healthy pregnant patients between 35 and 38 weeks' gestation were included in the study. Collected samples were fixed in 10% buffered formaldehyde. After routine histological follow-up, 4-6-µm-thick sections were cut, and histopathological and immunohistochemical examinations were made. RESULTS: Morphometric examination and endothelial, fibroblast, smooth muscle cell length, and vessel wall thickness were significantly different between the groups. In the placenta previa group there was an increase in ADAMTS-9 expression in fibroblast and some inflammatory cells in the subendothelial layer. In addition, negative expression of E-cadherin was evident with the separation of the areas of adhesion between endothelial cells and muscle cells in umbilical cord sections. Immunohistochemical analysis showed that endothelial cells, fibroblast cells, and smooth muscle in the placenta previa group expressed a positive level of VEGF-A. Increased hypertension and hypoxia occurring during pregnancy is one of the important causes of placenta previa. Its effect on extracellular matrix dynamics causes intercellular adhesion. The change in the production of VEGF-A was thought to play an important role in fetus development. CONCLUSION: ADAMTS-9 has been shown to be an important protein in cell-cell, cell-matrix binding and promoting vascular development. E-cadherin, which is the determinant of the cell binding complex, was thought to be able to increase VEGF-A expression and regulate angiogenesis by weakening cell adhesion. © Science Printers and Publishers, Inc.