Many mothers that I photograph say "oh! this feels so comfortable" when they slip into one of the maternity gowns I have. You can view a better selection and choose to purchase your own if you wish (they make GREAT dresses for baby showers, and just to look pretty in! on Etsy. For maternity sessions, you can go as glamorous or as comfortable as you want! Be sure to bring comfy shoes!
Be sure to check out my Maternity Look Book for the lovely maternity gowns I have on hand photographed on different women of all shapes and sizes. New gowns are added from time to time.