We chose not to get the vaccine in the hospital. I simply did not feel right about exposing my newborn to something straight out of the womb. Also, hep b is spread through sex or IV drug use. The vaccine is only effective for 15 years. She simply does not need it! The reason they give the vaccine in the hospital is in case the MOTHER is infected. In that case, the newborn can avoid contracting it. They can't discriminate by giving it only to people they think may have it, so they give it to everyone.
I don't know why we didn't hold off much longer, but we ended up getting it with her first vaccinations at 2 months. When I have another child, I will delay all vaccinations until his/her system is more developed.
I have just learned recently that the Hep b vaccine contains high level of aluminum (as do other vaccines). It is not proven whether this is safe or not. However, according to the FDA, a 12 -pound 2 month old baby could safely receive 30 mcg of aluminum per day. The Hepatitis B vaccine has 250 mcg of aluminum in it. That is enough for me to want to wait until more is known about these vaccines.