Will my belly be any smaller right after giving birth?

tmp-9287574

I know, I know. This is a really strange question, but hear me out because it has nothing to do with appearances.

I had the perfect PJ set picked out to take to the hospital with me. It's a really cozy 2-piece PJ set with a top that buttons up. It had always been way too big on me, so I thought it would be perfect!

I tried it on the other day and the top is just the teensiest bit too small now. I still have 3 weeks 'til my due date. Is there any likelihood that my belly may be a bit smaller after giving birth and I'll be able to wear them, or should I just give in and buy a bigger pair?