No.. Its perfectly safe for the baby as long as you have a professional there for emergencies. But those would'nt be because of a water birth, unless you keep the baby in the water to long :)
Water birth is just in the water. My mom told me that it feels better for the woman because she can just float instead of sit in a bed...
A water birth can also take place in your home rather than in a hospital. That's when the midwives come in. :P
does it make a difference for the baby