During 1930’s London, parents used to hang their babies out the window. Literally! They dangled in what were called “baby cages.”
Allegedly, it was important to do this so that babies could be aired out.
In the book The Care and Feeding of Children, this is what Dr. Luther Emmett advised mothers to do:
Fresh air is required to refresh and purify the blood, and this is just as necessary for health and growth as proper food. (With fresh air) the appetite is improved, the digestion is better, the cheeks become red, and all signs of health are seen.