I've had 3 babies. My first weighed 9lbs 3 ounces, I gained over 60 lbs. She was 21 inches long.
My second was 8lbs 2 ounces, and was 20 inches long. I gained 10lbs.
My third was 9lbs 4 ounces, 21 inches long and I gained 40 lbs.
First pregnancy was SAD diet, last two Mcdougall. My blood sugars were perfect for the last two and eh for the first.
Ironically enough, my middle girl who was my smallest at birth, has the most pudge and my last who was my biggest is my leanest!!
I believe the only time in our lives we lay down new fat cells is infancy and teenaged years. While of course they lay down new fat cells in utero, unless the women is diabetic and obese does it cause the issues you mention.
And I should add, while my middle girl is pudgier than the other two, she is in no way fat and I believe eating this way will keep her from being obese as an adult too. Just as I believe eating this way would keep a lot of kids no matter their birthweight from getting obese in later years.
As a side note, my hubby is the last of three kids and was his moms largest at over 1.5 heavier, and is by far leaner than his siblings even with his less than ideal diet