B..
My pediatrician actually told me not to use it. My son in over 3 now, so their formulation might have changed. When he was an infant, the amount of fluoride exceeded what is deemed acceptable by the EPA and other groups. Not only that, doctors say that newborns should not be given too much fluoride. (The same reason there is no fluoride in infants toothpaste, and it's only added in toddler pastes.) Nursery water has ADDED fluoride, that exceeds what is found in tap water.
Personally, I used filtered water...but was not afraid to use tap, if needed.