The purpose of the present study was to gain further understanding of the function of microRNA-18a (miR-18a) expression in the JEG-3 human trophoblast cell line. JEG-3 cells were transfected with pre-miR-18a mimics or miR-18a inhibitors. The effects of miR-18a on trophoblast cell invasion and apoptosis, and on the expression of estrogen receptor α (ESRα) were analyzed using a Transwell invasion assay, flow cytometry, reverse transcription-polymerase chain reaction, western blot analysis and a luciferase assay. The results of the present study suggested that miR-18a expression suppression led to a decrease in JEG-3 cell invasion and an increase in JEG-3 cell apoptosis, by inducing ESRα expression. The present study provides evidence for the involvement of miR-18a in the pathogenesis of pre-eclamptic pregnancies.