Around week 14, my regular pants starting getting too tight.  This was a lifesaver.  It allows you to keep your pants up, yet conceals the fact that they're not buttoned.  I was nervous it would be noticeable but it hides it well and holds them up, without being uncomfortable.

Around week 25, I was in maternity pants but as maternity pants can droop (especially the jeans), this helped keep them up.  Again, comfortable.  I wore this until the end of my pregnancy, and it always looked like a white T-shirt underneath my maternity top.

Postpartum, this was also a lifesaver.  For the first three months, I still had to wear my maternity pants unfortunately, but obviously the only way to keep them up was this band.  Then when I began to fit back into my regular jeans but wasn't quite there, this helped me keep them closed until I could button them again.

This is a great product for all maternity stages and it's really a necessity.  The only thing I would recommend, if this price seems high, is to check out other knock offs.  For example, Target makes a band similar to this that is supposedly much less expensive though I have not tried.