Microplastic (MP) contamination in the human body is an emerging concern in biomedical science, particularly due to recent evidence indicating their translocation into systemic circulation and placental tissue. This literature review evaluates current research on the presence of MPs in human blood and placenta, highlighting the clinical implications and the efficacy of two advanced spectroscopic techniques, Raman spectroscopy and Fourier-transform infrared (FTIR) imaging, for in situ detection. Research published between 2015 and 2024 was systematically reviewed using MEDLINE and ScienceDirect, focusing on observational human studies that employed spectroscopic MP detection. The search strategy incorporated keywords such as “microplastic translocation,” “human blood,” “placenta,” “Raman spectroscopy,” “FTIR imaging,” and “fetal-maternal health.” Microplastics were detected in 88.9% of analyzed blood samples, with polystyrene, polypropylene, and polyethylene being the predominant polymers. Placental tissues showed a median of 12 MP particles per 10 grams, mainly localized in the chorionic villi and maternal decidua. Raman spectroscopy demonstrated superior sensitivity for detecting smaller MPs, especially nonpolar polymers in digested samples, while FTIR was more effective for larger particles in whole tissue sections. Clinically, MP presence was associated with elevated inflammatory markers such as C-reactive protein and interleukin-6, prolonged activated partial thromboplastin time, and increased fetal liver enzymes, suggesting systemic inflammation, immune modulation, hepatocellular stress, and potential impairment of placental function. The findings underscore the biomedical urgency of understanding MP exposure pathways and their effects on fetal–maternal health. To advance diagnostic precision and maternal–fetal care, it is recommended that future biomedical research integrates standardized MP detection protocols into clinical toxicology workflows and explores targeted molecular biomarkers for early identification and risk stratification of MP-induced placental dysfunction.