I think along with growing a child in the womb, pregnant women should grow a third arm. Not only would this allow us to carry the baby and make dinner, it would allow me to open the door to my office while juggling papers, bottles and baby equipment.
It would need to be a strong arm, but not necessarily another right (or for lefties, left) arm. I'm used to carrying babies on my left side to leave my right arm free, so I really only need one of those. I don' t know exactly where it should grow though.
We're lucky to grow that extra eye in the back of the head when we become a parent but an extra brain would come in handy too.
I've decided my equivalent of Dumbldedore's pensieve is a list!