India will surpass China as the world's most populous country by 2027, according to the 2019 UN World Population Prospects report.

Both countries make up about 37% of the entire global population equal to nearly 7.7 billion, with China and India currently home to about 1.4 billion and 1.3 billion people, respectively.

"Between 2019 and 2050, 55 countries or areas are expected to see their populations decrease by at least 1%," the report noted, citing low-levels of fertility and an elevated level of displacement.

"In the largest of these, China, the population is projected to shrink by 31.4 million, or 2.2 per cent," the report indicated, expecting China's population to reach 1.1 billion, compared to 1.5 billion forecast for India.

China has already been trying to increase its population decline for years overturning its infamous One Child policy to encourage couples to have more children.

"Many of the fastest growing populations are in the poorest countries, where population growth brings additional challenges"United Nations Under-Secretary-General for Economic and Social Affairs (DESA), Liu Zhenmin, said in a statement.

The report also expected the following countries to become overpopulated by 2050: India, Nigeria, Pakistan, the Democratic Republic of Congo, Ethiopia, Tanzania, Indonesia, Egypt and the United States.