One great uncle (born in the 1880s) was 2 pounds at birth, and he, like others mentioned here, lived in the warming oven of the wood cookstove for several months.
One winter when he was in his 60s, he decided upon a goal: he wanted to be able to say he'd gone from 2 pounds, to 200. So, he spent all winter relaxing and eating, hit 200 pounds by March, went back to his normal diet, and immediately dropped back to 140... but he had reached his goal.
Amazing images... we're at 8 months gestation now, and our older children are really fascinated by unborn baby pictures, because they like to know what their sister looks like, how big she is, etc...
I was a preemie (3 lbs. 3 oz) in the early 50's when a lot of them either didn't survive or developed blindness in the eyes due to the hot lights of the incubators. Fortunately, my hospital was aware of the problem and protected my eyes for the several weeks I was in an incubator. However, I met another woman my age, also a preemie, who had very limited vision, almost legally blind, so I wonder if her problem was due to incubator lights.