What are the motifs in Bumped by Megan McCafferty?

The need for procreation is a recurring idea in the story. The human race is in danger in this futuristic setting. Roughly three-fourths of the population has a virus that eliminates their ability to procreate after reaching adulthood, somewhere around eighteen to twenty years of age. The obvious impact is a huge drop in births that literally puts the human race in danger of extinction. In an effort to deal with the problem, teenage girls are encouraged to have sex and put their babies on the market for sale though many babies are simply offered up for adoption.