Belly bands are designed to support the lower back and abdomen during pregnancy. These flexible support garments have many benefits such as; 
Help support your lower back and baby bump during activities, which can result in decreased pain overall.
Sacroiliac (SI) joint pain  supporting this region with a belly band can help stabilize the joint, which may prevent pain during activities.
Round ligament pain: This symptom occurs during the second trimester. It’s described as anything from a dull ache to a sharp pain on the front of the hip and below the belly.
Caused by the extra weight and pressure on the ligaments that support the growing uterus, it’s a temporary but sometimes unbearable problem. Belly bands help distribute the weight of the baby across the back and abdomen, which may help relieve the pressure on the round ligaments and reduce pain.