I m 23 weeks pregnant, and having igg +ve.for rubella, cytomegalo virus and herpes simplex virus....is it affects my baby?

Actually good news: The tests mean you have immunity to those germs and your baby is not at risk from an infection from any of those mentioned. Any germ on that list can infect a mom for their first time during pregnancy & cause a miscarriage, birth defects or worse. This is not a guarantee everything will go well but it is good news just the same.

Unclear.: If you test positive for igg for those three diseases at 23 weeks, then it is unknown what the implications are. The tests tell you that you have had prior infection with hsv and cmv, and that you either had a prior infection with rubella or you were vaccinated for it. The tests do not tell you when, so it is possible you were infected with one of these early in your pregnancy.