Mary, I don't know about all vaccines, but if a mom has natural immunity to measles (from having had the disease not the vaccine), this supposedly interferes with the vaccine given the baby. I think this is the reason for moving the vaccine to be given at 15 months. Although in Hawai'i, this has been moved back to 12 months again. I am not sure if this is how it is elsewhere. I don't think much research has been done on this, but at some point the effect of the mom's immunity supposedly no longer intereferes with the vaccine. I haven't been able to get clear info on this from our doctor or my own research. For myself, I had the measles as a child, so I have made the decision to delay the vaccine for my nursing toddler. I am sure our doctors on the list will have more to say. What say you, Dr. Rob? :D Aloha, Gloria Thai LLLLeader Hawai'i _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]