Introduction: Toxoplasma gondii is an obligate intracellular protozoan para-site that can infect any warm blood vertebrae, and if first trimester pregnant woman infected, it may cause abortion. The objective is to prove the effect of the Toxoplasma gondii concentration in anti-toxoplasma IgG-IgM antibody levels, and the outcomes of Balb/c mice pregnancies. Materials and Methods: The study was conducted in Balb/c mice with inclusion criteria, and was con-ditioned pregnant. The pathogen strains of Toxoplasma gondii tachyzoite in-jected intraperitoneally. The blood samples were taken serially to be tested for anti-toxoplasma IgG-IgM antibody levels. After the mice were injected with tachyzoite, they are assessed every day to observe their body weight, vaginal bleeding, and labor. Anti-toxoplasma IgG-IgM antibody levels examined us-ing qualitative mouse IgG-IgM antibody ELISA KIT. Results: Anti-toxoplasma IgM antibody levels increased significantly after 24 hours of injection tachy-zoites in all dose groups, and remained high through day 21. Anti-toxoplasma antibody IgG levels increased significantly after 72 hours post injection and remained elevated until day 21. The incidence of abortion is 100% in mice which injected tachyzoite levels 1 × 103 and 1 × 104, and the incidence of abor-tion approximately 2 - 4 days post injection. 100% of mice that were injected with tachyzoites 1 × 101 and 1 × 102 have labor at term. Physical anomaly was found in baby mice from mice that were injected with tachyzoite 1 × 102. Conclusion: There is a significant correlation between the concentrations of Toxoplasma gondii tachyzoite with anti-toxoplasma IgG-IgM antibody levels
