Pregnancy/Childbirth exercise videos - worth it?

[MrsFogi]

I've made the mistake of buying a pregnancy magazine and am now thinking of all sorts of things I never knew I needed! Has anyone tried any of the yoga/pilates/exercise for pregnancy and/or childbirth videos - are any of them worth buying?

I have a Shiva Rea yoga DVD , which has the advantage of being one of the only ones on the market (at least as far as I could see) which could be done from the first trimester: there are three women and you follow the right one for your trimester.

Having done yoga on and off for about ten years, I found it to be not as taxing as it might be (but then, it is for pregnancy...) but I have found it to be quite useful for sacro-iliac pain / general grumpiness in my pelvis. (And cheaper than the osteopath!) The other thing I like about yoga generally is that it makes you breathe properly for the duration of the session - I'm guilty of very shallow breathing, then finding myself out of breath.