Are you suppose to sleep laying on the back during pregnancy? i find it uncomfortable any other way but heard this is bad for the baby?

Some basics: You need adequate restorative sleep to support a healthy pregnancy. Your sleeping position will be of little importance until the last trimester when the enlarging womb can press downward on the arteries supplying your lower torso & the fetus. There are some concerns decreased blood flow could occur. So early on anything is fine but later in the process sleeping on a side is preferred.