I'm not sure there's any hard and fast rule to be honest, but I think it's due to the changes that the breast goes through in the early months.. Personally, my breast took about 6 months to settle into its 'final' shape, but it's now a lot wider than my natural breast, so I wouldn't be able to find an underwired bra that would fit both breasts, whereas the non-wired bras are a bit more 'forgiving' and stretchy.
Early days for me as I only had a Mx and LD flap last week - but is there a reason why we can't wear underwired bras if we can tolerate them. I always wear this type and was quite well stocked up prior to the op.
Many thanks K M x
Another vote for the Royce Bras. I really like the silver one and am thinking of "converting" to this model for my long term regular bra.
I had a DIEP reconstruction in April 2012 and I am still not able to wear my old 'normal' bras. My shape has changed and underwired doesn't work anymore. Royce do a lovely non-wired selection of bras specifically for reconstructed breasts. They have their own website, but our local BHS sells and fits them too.
Hope this helps.
I was told 6 months, but in the end waited a year... it was so nice to have pretty bras again, that said I still revert to my sport bras for every day!