To our knowledge, we report the first case of in utero infection in humans due to Pasteurella multocida in the first trimester of pregnancy. After antibiotic therapy was initiated, the mother recovered rapidly from bacteremia but the fetus was spontaneously aborted. Pathological examination of the fetus and placenta revealed acute deciduitis and chorionitis, indicating an infectious etiology for the abortion. The clinical and pathological features of this case are compared with those of the five previously reported cases of P. multocida bacteremia in humans that occurred during pregnancy.