I understand I should avoid falling asleep on my back and also limit how long I can lie down on my back during the day (i read limiting it to 5-10 min if needed). But what about lying down on the back with big pillow under my neck and upper back? I guess the angle that is created is eliminating the pressure on the vein that is of concern? Is there some sort of a guidance that you can lie on your back for prolonged time during the day given you are not lying flat and have some angle from big pillows? Sorry if it is a silly question but I don't seem to find an answer to that.