Order up a size or 2! I normally wear a lg and ordered xxl, which fit perfect. I have a similar fitting undie from motherhood maternity and the xl fits bigger than this does. But I LOVE the cut of these in the front! They are cut VERY low and don't irritate my bump at all! Only reason for 4 stars, is who wants to have order up 2 sizes!? The material is very thin, but I love it that way.