Placenta is a highly specialized organ that is necessary for successful gestation. Several models of the placental barrier are used to study how it functions, including the transplacental transport of xenobiotics. One of these models, human choriocarcinoma cell line BeWo is widely used in vitro. Notably, cancerous BeWo cells form multilayer structures that normally are not found in the human placenta. Here, we aim to develop techniques suitable for monitoring BeWo b30 cells in culture. To assess the state of BeWo b30 cells growing on a membrane, we use impedance spectroscopy, which allows us to estimate the number of cell layers by the change in the electrical parameters of the biological system. In mature BeWo b30 cell cultures, we also note a significant increase in the expression of genes encoding metallothioneins (particularly, MT1B, MT1F, and MT2A) and syncytins (ERVW-1 and ERVFRD-1), which can be used as biomarkers reflecting the development of mature phenotypic characteristics, namely, trophoblastic invasion and formation of the syncytium.