The war had kept men and women apart and so fewer babies were born in the war.
When men came home from fighting overseas in the forces, the first thing they did was to start a family.
The numbers of babies born in 1946--1948 grew rapidly. This time was called the 'baby boom'. Your grandparents may be baby-boomers – ask them. For a while, looking after a young family kept women at home, unless there was granny to help.
