"Also, that crowning will feel like your fanjo is on fire, but that it will be over quickly"
That's so funny findtheriver - because that's almost exactly what I say. I actually finish the class with a round of quotations (from Bounty, not mumsnet) from mums, one of which is "When you feel your fanjo is on fire, baby is nearly here, not long to go"....
And I yak on and on and on about panting, listening to the midwife, the urge to push like mad to get past the pain at the end (try not to!), or alternately holding it all in because it hurts too much to push (you're going to have to let go or that baby's not coming out!). I often do exercises which get the mums to gently bear down to identify where in their body they're going to feel the stretch and the pressure (tend to cover this bit in the women only class - understandibly. One day someone's going to crap themselves in class - me probably!).
Not sure how much people take on board. At my local hospital they have almost everyone sitting on the bed in second stage, being told to 'hold your breath, put your chin on your chest and push down hard into your bottom'. They don't encourage women to change positions if they're making slow progress, and there's lots of shouting and bullying going on to get the baby out as fast as possible, even when everything's progressing fairly normally. I'm sure that's why so many of the mums I see end up with bad tears. Makes me a bit sad really.
I don't tell people it's going to be agony - but some of the quotations I use from mums who've been there make it quite clear that some people find pushing and crowning excruciating.
On a personal note, just thinking about it makes my eyes water. First time round I'd had an epidural so didn't experience the sensation of pushing and crowning. Second time round I pushed out an 11 pounder with no pain relief. Bloody hell, it hurt beyond anything I could ever have imagined. Getting that out the way was the biggest relief of all time. You should have seen my face in the post-birth pictures. I must have had enough endorphins and oxytocin in my system to floor an elephant.