There's no set time when you need to, or have to, start using a pregnancy pillow. To put it simply, you should start using one whenever you start finding it difficult to change positions during sleep. For most women, this is around week 20, when your belly starts to expand.

Being in this position maximizes blood flow to the uterus without putting pressure on the liver. Women who experience hip or back pain during pregnancy may find that placing a pillow or two between the knees or bending the knees during sleep can help provide relief.

U-shaped pillows offer comfort on both sides of you, so your belly and back are supported, but they can take up a lot of room on your bed, as mentioned above. A C-shaped pillow may work better for some, but you won't find the same back support as with a U-shaped one.

Your growing belly means two things for your sleep setup: limited options for safe sleep positions and new pressure points for the positions that actually are safe for sleep. Unfortunately for back and stomach sleepers, side sleeping is best during pregnancy.