Why has the overall rate of human population growth declined since the second half of the 20th century?

The decline in the global human population growth rate since the second half of the 20th century is primarily driven by a widespread reduction in fertility. While mortality rates have also decreased, the shift toward lower birth rates has become the dominant factor in slowing population expansion.1

This trend is largely explained by the demographic transition, a pattern where societies move from high birth and death rates to lower levels of both as they industrialize and urbanize. Key drivers of this decline include:2

• Socioeconomic Changes: In modern industrial societies, the cost of raising and educating children has increased significantly, shifting the economic incentive away from having large families, which were once beneficial for manual labor and old-age security.23
• Access to Resources: Increased availability of contraception and family planning services has allowed couples to consciously restrict their fertility.453
• Empowerment and Education: Greater education and employment opportunities for women have been instrumental in reducing fertility rates.53
• Age Structure: As mortality rates fall, populations age, resulting in a smaller proportion of people in their reproductive years, which further contributes to lower growth rates.1

While coercive family planning, such as China's former one-child policy, has been used in some regions, such measures are widely condemned, as the right of individuals to determine their own family size is an essential ethical principle.3