My cat has been super-lovey-dovey-on-mommy with each pregnancy, starting sometimes just before I found out for sure I was pregnant. This is my third pregnancy and now that I'm finally due (in less than 3 hours--of course "due dates" are hardly accurate) he is even more all over me. He has been more aggressively playful with adults and is spending more time around the kids, even though they are just as rough with him at times as ever. He is the most tolerant cat in general, but seems to just want more family time rather than waiting to love on us when the kids are asleep.
With my first pregnancy, he woke me up around 4:30 in the morning, every morning, and insisted I come downstairs with him. If I didn't go all the way, he would run ahead, realize I had snuck back up to bed, race back upstairs tripping me or scratching our door whining until I walked him all the way downstairs again. It drove me nuts, but my vet said cats know when we're pregnant and he probably just wants to love on me more. This time he had his annual visit a month ago and he had gained just enough weight that they mentioned he should not be gaining any more. He is still healthy, but they do not want to see any more gain. They also said it might be pregnancy-related stress eating on his part since he is only six and a half years old, so hopefully it will come right off him. Many animals react to pregnancy--I've even heard of pet iguanas (males) attacking their female owners during certain times of the month or pregnancy. Animals are very in-tune with their human families. =)