Repeated Detection of Rubella Virus IgM Antibodies in Two Pregnancies Without Evidence of Fetal Infection: A Case Report and Challenges in Serological Interpretation.

Serologic screening for rubella virus, as part of TORCH testing during pregnancy, remains a cornerstone in the prevention of congenital rubella syndrome. However, isolated detection of rubella-specific IgM antibodies may lead to diagnostic uncertainty, especially in the absence of clinical signs or supporting serological evidence. We present a case of a pregnant woman who tested positive for rubella IgM antibodies during two consecutive pregnancies, despite lacking any sonographic or serologic indications of fetal infection. Both pregnancies culminated in the delivery of healthy neonates with no clinical or laboratory evidence of congenital rubella. This case highlights the possibility of false-positive IgM results, persistent IgM antibodies, or nonspecific immune reactivity. Timely clarification of such findings is essential to avoid unnecessary anxiety and invasive procedures. Interpretation of rubella IgM results should always consider the clinical context, supplemental serologic tests (such as IgG avidity), and current epidemiological data.