hi
In my first pg i gained 22kg (i was 38kg when i fell and when i was last weighed at 35 weeks i was 58kg....i didn't have the baby until 37w)
Im pg with what i hope is my second so i'll let you know!
I think 10-13kg is the normal (according to dr miriam stoppard). 3-4kg is the baby. The rest is the baby's support system, your uterus and breasts. Your own fat stores will usually account for the same weight gain as your baby.
HTH