In my historical interpretive studies for mid-19th Century American (US) life, the figure given for childhood mortality, under the age of ten, was 50%....so Americans, at that time, could expect to lose half their children before they were ten years old. A high childhood mortality rate was one of the reasons folks were given to raising such large families then (10 to 17 children were common)...the other being that, in a largely agrarian society, extra hands were needed to run the farm.