Subclinical rubella reinfection in pregnancy: report of a case.

A G1 PO, 25-year-old woman, who was confirmed to have a natural immunity to rubella before pregnancy, was found to have rubella reinfection with positive rubella IgM antibody at seven weeks of gestation. At 23 weeks' gestation, she received fetal cordocentesis in which fetal blood tests were negative for rubella-specific IgM. There were also nonspecific findings in detailed sonographic examination. Thereafter, she delivered a healthy, female baby at term. Rubella IgM was not detected in the infant blood at birth and IgG subsided after the first year of life. A primary attack of rubella does not always indicate lifelong immunity; reinfection can occur. Although the symptoms of rubella reinfection are mild and the risk to the fetus from maternal rubella reinfection during pregnancy seems to be lower than that of a primary attack, prenatal evaluation of intrauterine infection by cordocentesis after 23 weeks' gestation should be considered.