That during labour you may need to poo, to the extent that you actually stop thinking about the abby at all, beyond a, 'If I could just have this poo, I'd be happy to get on with labour. And sod the fact that I've got an audience, I'm having this poo - or else!' 
That, poo-breaks included, some labours are really very fast - so fast that you may not clearly remember them afterwards and may have to rely on dh's account of things. That he may want to remind you about the poo.
That a few minutes after birth you will feel utterly winded and thus unable to eat the cheese sandwich that the mw has brought you, despite the fact that you are ravenous. That you will then have to watch your dh scoff the sandwich.
That in the bath afterwards you will go to wash your fanjo and wonder why it feels like the horn on a clown's car. You will exclaim in horror and have to make up some story to the nurse supervising you, because you really don't want to tell her about the clown's horn thing.
That a week or so after giving birth you may suddenly find that you have the itchiest legs in the whole wide world. That they will be covered in hives and that you will want to claw off your own skin, just for a bit of relief from it all. That nobody will seem to have any clear idea what causes that, or how to stop it. No one ever, ever tells you that!