bad - no, true, I wouldn't want to equate 'mother' with that kind of identity either, obviously.
WoT - I think it would depend when you did it. I know people who say you want to get to junior lecturer level, have babies, and come back, but I don't see much evidence it works. I've seen people who are incredibly hard-working manage to have babies before the PhD, do the PhD with little ones, and go on from there - so the gap is before the PhD. But I think it is really tricky.
I think bigkids is right, the biggest issue is male academics not taking much leave, which ends up with a culture of presenteeism.
They only recently tried to make any sort of proper allowance for maternity leave in the big assessment that rates all universities' research outputs.