With progress of pregnancy the body produces hormone relaxin which makes you more flexible. But it is important to stay careful as this is the time when most women tends to lose their balance too.
Doing side stretching will make you feel comfortable and will open your side waste and pelvis and stretch your hips too. Stretching lessen up the aches and makes pregnancy smoother. Make sure you stretch everyday in your pregnancy. It also works as a wonder for the little bean in the womb.
If stretching makes your uncomfortable and increase your pains do not continue.