The World Population Prospects 2019: Highlights, published by the Population Division of the UN Department of Economic and Social Affairs, said that the world's population could reach its peak around 2100, at a level of nearly 11 billion.
The report also confirmed that the world's population is growing older due to increasing life expectancy and falling fertility levels.
The age group of 65 and over grows the fastest and by 2050, one in six people in the world will be over age 65, up from one in 11 in 2019.
The number of countries experiencing a reduction in population size is growing.
Populations are projected to decrease by 1 percent or more in 55 countries or areas, of which 26 may see a reduction of at least 10 percent.
China's population is projected to decrease by 31.4 million, around 2.2 percent, between 2019 and 2050, the report said.
The report said that India is likely to overtake China as the world's most populous country around 2027.