A Pediatric opinion on water birthing
I won't repeat what Katana has stated already, so I'll tell you my concerns about water birthing from the pediatric end.
My chief concern with water birth in particular is the aspiration of the birthing tub's water with the first breaths of life. If the delivery goes smoothly and the child does not take a breath before being brought to the surface, I have no serious objection, but this cannot be assured. This water is not pure once the mother gets into it (even if it started that way). Bacteria from the skin, anus, and vagina all enter into the fluid. These are all organisms the child would be exposed to during normal birthing as well, but not in the lungs. This is a prime setup for pneumonia and sepsis.
Furthermore, water, even purified, is far from innocuous when aspirated into the lung. It disrupts the action of surfactant (essential for the normal function of the lung and notably absent/deficient in premies) and can cause a chemical pneumonitis. A child is capable of aspirating too great a volume of fluid in one breath to be reabsorbed before it causes significant respiratory distress (this is commonly known as drowning!)
Depending on the fluid aspirated, significant electrolyte derangements can also result from aspiration, most notably hyponatremia which carries the very real risk of seizures.
As to it being "more natural," it's a bunch of woo-woo. It makes as much physiologic sense and trying to breathe underwater as an adult because hundreds of millions of years ago we had aquatic ancestors who could do so.
We are lucky in pediatrics that things usually turn out so well. Children are resilient, and most births will go well no matter what we do (the survival of the species is testament to that). Sometimes they don't. Having cared for more children than I care to think of who have sustained mental retardation and cerebral palsy from normal births gone tragically awry, I encourage everyone to stack the odds in your child's favor. That means not taking unnecessary risks. This is one professional's opinion, take it for what you will.
Br0k3n, best of luck, and congratulations on your upcoming birth!