Although the mechanisms underlying their roles in transplacental antibody transfer remain to be extensively studied, Gu et al. [20] as well as Morales-Prieto et al. [21] showed varied observations in their studies where miR-199a is deregulated primarily during tumorigenesis and hepatitis and equally plays an important role in the regulation of COX-2 expression in pregnant myometrium by blocking overexpression of TNF -alpha-induced myometrial cell contractility. The gene discussed is TNF; the disease is hepatitis A virus infection.