Congratulations at your lovely news.
how very sensible to begin thinking of how the cats and the baies will interact at this stage.
You can get special tapes of babies crying - actually, of all sorts of stuff - hoovers, washing machines etc, which you can play to your cats to get them used to the hubbub of life in a "full to capacity for the time being" family setting, which will help them to get used to the idea of a crying baby before the real thing arrives. You could buy one or two extra "baby things" and leave them lying around where the cats can investigate, and when the baby arrives, you can do scent swapping, just as you would when introducing a new ktten. the best way to do that is to have something which will smell of both Mum and Baby, or Dad and baby, so you mingle the familiar scent with the new scent.
If your cats enjoy cuddle time, when the baby comes, try to make sure that all the fuss isn't centred just around the baby, and make sure you make time for the cats too - with two cats at least they have each other for snuggling and playtime.
Cats seem to have an innate instinct which steers them clear of babies generally (creatures of uncommon good sense
) , but we do know of a couple of friends with cats who had children, and the cats would sleep in the cots/pushchairs, sometimes whilst the babies were still in them. Maybe not ideal, but their children certainly didnt come to any harm over it.
I've heard it said when I was a kid that cats would suffocate babies, but I've never actually heard or read of this happening. Some very sweet photos of cats and babies here
https://www.google.co.uk/search?q=cats+sleeping+on+babies&biw=1024&bih=1201&source=lnms&tbm=isch&sa=X&ei=RgATVIfEDYPKaP6ugcAC&ved=0CAYQ_AUoAQThe "oh-oh" time for families is when the babies get to crawling and toddling stage, because that's when they have a habit of grabbing and pulling and walking over anything and everything as they expore. That goes down less well with cats generally, but baby-gates can be had these days with small cat flaps built in, so the cats can get out of harm's way, and the baby stays put (that's the theory anyway - I havent tried one personally!).
The main thing is never to leave the baby with the cats unsupervised, same as I'd say for dogs really, but I think you probably already embrace that philosophy.
