Baby was born tiny with excess loose skin
What was the birth weight?
How do you define tiny?
Edit: just caught up with your latest post.
For comparison, our son was 7 lbs 9 oz at birth and was very wrinkled.
He had what I can best describe as "old man's legs".
Not plump but saggy and wrinkly in the thighs.
His feet were also bent over at the ankles because he was too long for the womb.
No issue with GD.
No low carbohydrate diet either, though.
We are pretty sure that he was under nourished in the womb because he didn't stop eating continuously for the first year.
By 5 months he was huge.
So I doubt that a low carbohydrate diet was responsible for a low birth rate or wrinkly skin.
These things happen.