My rubella is neg in first pregnancy what does it means?

Not rubella immune: I assume you are referring to testing done during pregnancy to test for immunity to rubella from prior immunization or infection. A negative test indicates either no immunity or such low antibodies that it is not detectable. Rubella is a mild infection to children or adults, but during early pregnancy, causes fetal birth defects, esp deafness, and congenital eye and heart abnormalitie

Immunity or not?: Your Rubella test should have given you a value to indicate immunity or not. If there is "no immunity" your OB will tell you that you have risk to your unborn child of malformations when exposed to Rubella. (German measles).