The report, released today, said most of the population growth will occur in developing regions which are projected to increase from 5.9 billion in 2013 to 8.2 billion in 2050.
During that same period, it said, the population of developed countries is expected to remain largely unchanged at around 1.3 billion people.
The report said much of the overall increase between now and 2050 is expected to take place in Africa and developing countries with large populations such as India, Indonesia, Pakistan, the Philippines and the United States.