The world’s population reached eight billion on Tuesday, 12 years after passing the seven-billion milestone, the United Nations said.

It would take approximately another 15 years – or until 2037 – for the population to reach nine billion, which shows that the overall growth rate is slowing, the global body said in its World Population Prospects 2022 report.

Projections by the United Nations suggest that the global population could grow to around 8.5 billion in 2030, 9.7 billion in 2050 and 10.4 billion in 2100.

“The milestone [of 8 billion] is an occasion to celebrate diversity and advancements while considering humanity’s shared responsibility for the planet,” UN chief António Guterres said.

Asia was the most populous region in the world in 2022, the report said. Eastern and South-Eastern Asia had a population of 2.3 billion, or 29% of the global population, and Central and Southern Asia had 2.1, or 26%.

China and India together accounted for over 1.4 billion people, or over 17% of the global population.

The report said that India is projected to surpass China as the world’s most populous country in 2023.

According to the report, over half of the rise in global population till 2050 would come from eight countries – India, Pakistan, the Democratic Republic of the Congo, Egypt, Ethiopia, Nigeria, the Philippines and the United Republic of Tanzania.

It said that population growth is caused partly by increased levels of life expectancy at birth. Globally, life expectancy reached 72.8 years in 2019, a rise of almost 9 years since 1990. A drop in mortality is also expected to lead to an average longevity of around 77.2 years globally in 2050, the report said.

In 2019, life expectancy at birth for women exceeded that for men by 5.4 years globally. Female and male life expectancies stood at 73.8 and 68.4.

“Following a drop in mortality, population growth continues so long as fertility remains at high levels,” the report said. “When fertility begins to fall, the annual rate of growth starts to drop.”

It said that the average fertility stood at 2.3 births per woman for her lifetime, falling from about 5 births per woman in 1950. Global fertility is expected to decline further to 2.1 births per woman by 2050, according to the report.

It also said the global population growth rate dropped below 1% per year in 2020 for the first time since 1950.