These issues happen as the tummy rests on the intestines and
main blood vessels like the vana cava and aorta upon you sleep on the back.
-- During pregnancy the baby may actually press on
the main blood vessel that returns blood to the heart.
By clogging
the main blood vessels, the blood supply to other organs of the body is reduced, particularly the lungs, liver and kidneys, leading to malfunction of these organs.
The most common blockage point is in the lower abdomen where the aorta,
the main blood vessel leaving the heart, forms two branches going to the back legs (** see Rough Diagram **).