In Children Of Men - How does Cuar'on use setting to reinforce the central ideas of hope and despair?

A work of science fiction, this novel is set in a futuristic London, but not so far away that the reader cannot imagine it. A world without children is unimaginable.... for people to consider the end of humanity would lead to total despair. Thus, we see parental urges being satisfied by caring for animals..... for puppies and kittens. None-the-less, hope lies in an unborn child and systematic physical examinations of people in their child bearing years keeps the hopes of continued humanity alive.