5.8 Causes and Effects of Demographic Change

• China's population has fallen every year since 2022, the first declines in about six decades.
• China began raising its retirement ages in January 2025, step by step over 15 years (for men, from 60 to 63).
• In 2025 China announced a national childcare subsidy for children under three, part of a push to raise the birth rate.

China introduced the one-child policy around 1980 to slow population growth. It was enforced with fines, pressure and, at times, forced procedures, and it contributed to an aging population and an imbalance of more boys than girls. China moved to a two-child policy in 2016 and a three-child policy in 2021, but birth rates kept falling because of high costs of housing, education and child care. Policy can limit births much more easily than it can raise them.

Hundreds of millions of Chinese have moved from rural areas to cities, and from the interior to the coast, since reforms began. The hukou (household registration) system ties access to public schools, health care and benefits to where a person is registered, usually their birthplace. Many migrant workers live in cities without full access to services. Reforms since 2014 have eased registration in smaller cities, but the biggest cities remain hard to join. Mexico City and Lagos also grew rapidly, straining housing and transport.

Migration shapes politics too. Rural migrants in Chinese and Nigerian cities often live in informal housing with poor services, and immigration was a central issue in the UK's Brexit debate.

Highly educated people have left Iran and Nigeria in large numbers, often pointing to limited opportunities, corruption or repression. Nigerians call this wave of emigration “japa.”

Fast population movement strains housing, transport and services, concentrates skilled workers in some places and drains them from others, and can raise crime where cities grow faster than policing and jobs. It can also fuel new parties that oppose immigration or supranational bodies like the EU.

States respond with policies that shape behavior, like encouraging or discouraging births, and with rules that protect religious minorities or discriminate against them.