I think they are to support your bump. especially from back pain... I never had one yet or with my other pregnancy. although I did break my back in between my boys so I might end up with one later on. I'm only 20 weeks so... although I've gained like 16 pounds.

My doc put in a prescription for one for my back bc baby's weight is hurting me. It helps more so when your sitting down. Atleast for me. It started to hurt me while wearing it being up and about. It also restricted my bending ability... More than I already am at the time lol so it just got annoying. I haven't really worn it that much. I just take a break when I notice my back starting to bother me real bad