Hey pretty Mama,
If you are in the latter stages of your pregnancy – yay you are almost there – chances that your lower back feels tight or sore are pretty high as your lower back is in perpetual flexion. By doing pelvic hip circles and moving your hips and pelvis gently you will help stretch out this area. You can do these standing up or sitting on the stability ball. Do 10-15 reps going in one direction then in the other. Do 2-3 sets total.
Be well and always smiling!