Oh please don't panic yet, "rubella antibody reactive" actually means your body has antibodies against rubella, which most likely means you were vaccinated before (or had it as a child) and are protected, not currently infected. The key thing your gynae will look at is whether it's IgG (past immunity, generally good news) or IgM (recent infection, which is the one that warrants more concern for the baby's eyes, hearing, heart, and brain development in the first trimester). My friend went through something similar at KKH and said the doctor explained it really clearly, they ran a follow-up IgM test just to confirm there was no active infection, and everything turned out fine. So the result on its own is not necessarily alarming, but the distinction between IgG and IgM really matters here, and it is worth going back to your gynae to ask specifically which antibody type came back reactive before you worry further. Do check with your doctor or a specialist to get the full picture for your specific results, they are the best person to interpret this for you and your baby.