Maternal rubella infection during pregnancy can induce more or less severe congenital defects. In France in 1989, 43 rubella infections in pregnant women were recorded by the National Laboratory of Health. Diagnosis of primary rubella infection rests on detection of specific IgM antibodies. The most reliable technique for detection of IgM antibody is the antibody-capture immunoassay. Presence of rubella-specific IgM antibodies must be interpreted with caution: specific IgM antibodies may occur following reinfection and there have also been reports of rubella-specific reactivity in sera collected after infections with other viruses. In some cases, presence of rubella-specific IgM antibodies cannot be ascribed to any of the reasons above and remains completely unexplained. Fetal infection can be demonstrated by detecting rubella-specific IgM antibodies in fetal blood. However, very sensitive techniques must be used in order to obtain reliable results. Today, widespread immunization is still essential. Immunization of all seronegative pregnant women immediately after delivery is especially important since most mothers of babies with congenital rubella were multiparous. Women exposed to rubella may be offered normal human immunoglobulins as soon as possible after the exposure ; if delayed, this treatment may be ineffective.
