LittleBairn - there's an MNer called GussieGrips who's downright evangelical about pelvic floor exercises, I think she's an HCP of some sort.
There was a thread recently where she said that a THIRD of women currently suffer some incontinence!! and that it can be generally be fixed (for most people) by doing pfe's three times a day for three months.
For the rest of us, we should be doing them once daily for the rest of our lives anyway!
I'm rubbish at remembering, probably do them three times a month, if that.... 
But yes, def a wise idea to ramp them up during pregnancy. I had a bit of incontinence for a couple of days after DS was born, it was not good.