出生率
Birth rates ranging from 10 to 20 births per 1000 are considered low, while rates from 40 to 50 births per 1000 are considered high. There are problems associated with both an extremely high birth rate and an extremely low birth rate. High birth rates can cause stress on the government welfare and family programs to support a youthful population. Additional problems faced by a country with a high birth rate include educating a growing number of children, creating jobs for these children when they enter the workforce, and dealing with the environmental effects that a large population can produce. Low birth rates can put stress on the government to provide adequate senior welfare systems and also the stress on families to support the elders themselves. There will be less children or working age population to support the constantly growing aging population.