Helps mother to conserve her energy. Promotes deeper relaxation. Water relaxes the pelvic floor muscles. Water stimulates the touch and temperature nerve fibers in the skin. It blocks impulses from the pain fibers, known as the Gate Theory of Pain.
Immersion is often more effective and safer than an epidural.
Facilitates a dysfunctional labor. Water can be an effective way to stimulate dilation of the cervix when the mother has difficulty progressing into the active stage of labor. Water can reduce the need for drugs to artificially stimulate labor. Often, simply getting into the tub will result in dramatic and rapid progress to full dilation within an hour or two. Lowering of blood pressure.