If you have had chicken pox in the past you can consider yourself to be immune to the virus in which case your baby is not at any risk. Even if you cannot recall ever having chicken pox it is important to emphasise that most adults have been exposed to the virus, which again means that you are immune and that your baby is not at risk. Furthermore if you are not immune to chicken pox the odds are in your favour that neither you nor your baby will contract the virus. Since you are already in the final trimester of your pregnancy the baby is not at risk of a congenital abnormality because if such a rare event were to occur it would tend to be associated with exposure during the early part of the first trimester. In summary your baby is not at significant risk but it would be appropriate to let your doctor know of your concerns at your next antenatal visit.