I'm 40+wks and have only put on 5kgs...all 3 preg's have been between 4-6kgs, but i'm also a bit pear shaped and tend to "absord" alot of my own body weight into the baby...i make jokes to the Dr that i have a couple of camel humps out back that sustains me and bub I've eaten pretty much anything i want....particularly chocolate but then once i have the baby, i lose about 8-12kgs straight away. I don't think my body is capable of putting on 20+kg during pregnancy, i'd be in some serious bad health....but a couple of my friends and sister's have put on 20-30kg with their preg's and managed fine. I think it just depends on your body...and as someone above already said, as long as both you and bub are healthy and being nourished, its all good, and i wouldn't be too worried.