What are the pros and cons of a water birth?

pros
For the mom, being in the water is quite relaxing and soothing.
The water is also invigorating, giving the mother energy when she most needs it.
The water allows the mother to float somewhat, making it easier to shift positions.
Also, the buoyancy allows better circulation of the blood and better contractions of the uterus, making the whole process less painful, and providing a better oxygen flow for the child.
The anxiety of childbirth will sometimes increase a woman’s blood pressure, but the water tends to lower it.
The act of physically relaxing helps the mother also relax mentally. This enables her to direct her energies toward the delivery process.
Some women feel the water gives them more privacy, thus relieving some of her anxiety.
For the baby, he will be more familiar with the water environment than an air environment.
As a result, the baby will feel more security and assurance.

cons
There might be a risk of the water entering the woman’s blood stream.
Although extremely unlikely, there is a remote chance that the baby might experience stress within the birth canal, and gasp for air. But if he’s in water, he would inhale water into his lungs. Again, this is unlikely, since a baby almost never inhales until exposed to air.
There is also a slight chance of the umbilical cord snapping when the baby is pulled to the water’s surface. However, this can be avoided simply by being cautious when lifting the child to the mom’s chest.

got that of this site

http://pregnancyrx.com/the_pros_and_cons_of_water_birth_is_it_right_for_you.php

The only con to a water birth is that virtually all ob/gyn’s will not assist. You can use the water all you want, but when you are ready to push out, then you have to get back in bed. So, it changes your caregiver choices.