Maternity Dresses vs. Normal Dresses

Ne
I just hit the 27 week mark and haven't done any maternity shopping as yet.
I've been making do with dresses the last few weeks, and because I've only gained in my stomach and most of my dresses are stretchy I don't know if I should bother with maternity dresses or just buy a bunch of normal fit (ahem, cheaper) ones.
Is there any reason I would need to go maternity? 👗