When a country's population grows quickly it has the following effects

• The large number of young people have to have services e.g. schools provided for them
• There are fewer older people, so less money needs to be spent on them
• There is a relativly small proportion of adults of working age; these people provide the wealth for the services
• There is pressure on the countryside with the extra population to feed; this can result in overgrazing, over cropping and soil erosion
• People move to the cities to find work; developing countries with rapidly growing populations have the fastest growing cities in the world
• Shanty towns grow up on the edge of cities; these are self-constructed buildings of poor quality which can lack vital services such as water, electricity and sanitation
• Some people apply to migrate to developed countries in order to improve their standard of living