I put on about 20kg in the pg... not enough exercise but i ate really well.
A friend of mine have put on exactly the same amount in different pgs, one she ate really badly and didnt exercise, the other she was the oppersite and it made no difference.

My best advice, enjoy your pg, eat well and dont beat yourself up for a little indulgence now and then and dont focus too much on your weight - there is a reason that OB's dont weigh you at every visit now - some people put on very little, others put on tonns and sometimes neiter affects your bubba.

My DH use to say to me that my extra weight is me protecting our baby, if i got sick there were some reserves for her! (i wasnt huge thou)

Enjoy your pg and get off the scales