We don't buy anything special, but we do tend to buy bigger sizes (not because they fit over the diaper, but because we like things to fit for awhile, KWIM?). Most baby clothes are stretchy--you just have to be careful with jeans or similar fabric that is not forgiving. I think it's adorable when Livi has cute little hand-me-down 6-12 mos Gap leggings on (she's 7 mos).........her cutie patootie sticking out the back. :LOL I think it grows on you.
On the other hand, it definitely depends on the diaper, because when I use prefolds I'm always amazed at how trim they are, and I have to keep squeezing her tushie so I know it's still there.
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