I am just under 5 ft, had my daughter at eighteen, was tiny and very slim, she weighed seven pounds eleven and a half, and I had an easy birth.
I was very lucky and snapped back very quickly even slimmer then before with tummy smooth and flat, but she was my only child and I often wonder if I had more pregnancies I would have been so lucky.
I did have a lot of morning sickness that lasted through the pregnancy so didn't eat too much, but she was born healthy and has never had any health problems and is slim.
It could be the luck of the draw, genetics, nature and/nurture, I knew how to look after a baby as my mum had a late pregnancy and I helped with my youngest brother. I read all the books before and after she was born, being a Service wife I did have good medical backup and the Families Officer was on hand to help if anyone had problems.
I didn't breast feed as non of us were, as far as I can remember I never had any problems she was just a normal baby growing up into a normal child and adult.
All of my brothers and sisters and I were skinny when we were kids and none of us have had weight problems.
I don't think obesity in a mother necessitates obesity in the child, its how the child is fed and looked after, and exercise as CLKD says, we were never in and rode our bicycles, walked to school sometimes miles and no junk food.