You might wonder why you need more circulation to build lean muscle mass. (musclenitxt.net)
It also helps to improve blood flow to areas of the body that need more circulation. (animalkindvet.com)
Bleeding might be more severe in a tub as the warmth might cause more circulation, and with a pre-term baby, the lungs may not be developed enough to handle the water should the baby breathe any water in. (checkpregnancy.com)