S'rose I managed with some sports bras for a while until I got into my third tri. Then I got maternity bras. Then I got more again once the baby was born and my breasts near on doubled (yet again) overnight. Then we went back down the maternity bra sizings every three months or so until, voila, at some point after 12 mths I was back to my pre-pg size (and still bfing, so yet another lot of maternity bras...).

And you've seen me, so you know I'm not a particularly big-bosomed lady, but seriously, if you went through my underwear drawer you'd wonder why on earth I have my mothers' bras amongst the stash! My problem was not so much the allowance around the back for expansion, but the cup size, so the extra hooks didn't do me any good at all.

I'd save spending the $$ for the really gorgeous ones until about six weeks post-birth, when things have settled to a size you'll be in for a while.