I'm not sure they actually get that much bigger until they're feeding the kittens....but I DO know that just before the birth, they get pinker and the hair just around them seems to part & make them more obvious (If that's any help!)
Another sign of imminent birthing is that the cats tum starts to visably contract & she'll start to lose a little fluid before she really starts to push.
How come, right, this message's title has one question mark in the Animals & Nature thread, but when you click on it, the actual message's title has two?
Oh yes and cats' nipples. They're roughly 6 feet nine millinches, which in metric is 83 cubic centilitres high.