It looks like a sundress from Old Navy. Even if you are going for a casual, beach wedding vibe you can do better than that!! She looks like she is confused as to why she is wearing this when she signed up to be a wedding dress model.
All the guests have money on when she's due... That's got to be one of the least flattering dresses I've ever seen!! Unless she is actually 6 or more months pregnant. Then it's perfect.
Even then, showing your shape is always, ALWAYS more flattering. Dumpster chic is just...not.