Unfortunately, two common favorite sleeping positions—on the belly and on the back—are not the best (and certainly not the most comfortable) choices during pregnancy. The belly position, for obvious reasons: As your stomach grows, it’s like sleeping on a watermelon. The back position, though more comfortable, rests the entire weight of your pregnant uterus on your back, your intestines, and major blood vessels. This pressure can aggravate backaches and hemorrhoids, make digestion less efficient, interfere with optimum circulation, and possibly cause hypotension, or low blood pressure, which can make you dizzy.
This doesn’t mean you have to sleep standing up. Curling up or stretching out your side—preferably the left side, though either side is fine—with one leg crossed over the other and with a pillow between them, is ideal for both you and your fetus. It not only allows maximum flow of blood and nutrients to the placenta but also enhances efficient kidney function, which means better elimination of waste products and fluids and less swelling (edema) of ankles, feet, and hands.
Very few people, however, manage to stay on one position through the night. Don’t worry (repeat: do not worry) if you wake up and find yourself on your back or abdomen. No harm done; just turn back to your side. You may feel uncomfortable for a few nights, but your body will soon adjust to the new position. A body pillow that’s at least 5 feet long or a wedge-shaped pillow can offer support, making side sleeping much more comfortable and staying on your side much easier.
If you don’t have either of these, you can improvise with any extra pillows, placing them against your body in different positions until you find that perfect combination for catching z’s.