Bovine genital tritrichomonosis is a venereal disease produced by the flagellate Tritrichomonas foetus. The disease is characterized by the repetition of oestrus and infertility due to embryonic or foetal death. Numerous experimental rodent models have been developed, but none of them has been applied in pregnant females. In this work, we reproduced genital tritrichomonosis in pregnant BALB/c mice. The results were analysed considering the following pregnancy phases: early, middle and final. In the infected group, embryonic loss was significantly higher and occurred in the early and middle phases, in accordance with the time of embryo death in infected bovines. In infected animals at the early phase of pregnancy there was evidence of embryonic death without inflammatory changes in the uterus, suggesting a pathogenic mechanism that does not involve direct tissue damage. In the later days, conceptus loss was associated with endometritis and changes in the decidua.