If the immersion is right, mother's body will respond by releasing more oxytocin, which helps to speed up the labor process. (attachfromscratch.com)
A herb often used in pregnancy to help speed up labor. (expressing-mama.com)
Furthermore, oxytocin production often increases when women are immersed in deep warm water, which can speed up labor without any increase in sensation / pain. (health-foundations.com)