This comprehensive review examines the effects of various infections on pregnancy, focusing on maternal symptoms, fetal outcomes, diagnostic methods, and placental pathology. The paper covers bacterial, viral, and parasitic infections, their mechanisms of transmission, clinical presentations, and histopathologic findings in the placenta. It emphasizes the importance of early detection and intervention, highlighting the challenges in diagnosis due to often asymptomatic presentations. The review also discusses the placenta’s role as a protective barrier and its immune defense mechanisms against pathogens. Overall, this paper serves as a comprehensive resource for understanding the complex interplay between maternal infections, placental pathology, and fetal outcomes.