India is set to overtake China as the world's most populous nation, surpassing it by 2.9 million people by mid-2023, according to United Nations data released Wednesday.

The South Asian country will have an estimated 1.4286 billion people against China's 1.4257 billion by the middle of the year, according to U.N. projections. Demographers say that the limits of population data make it impossible to calculate an exact date.

China has had the world's largest population since at least 1950, the year United Nations population data began. Both China and India have more than 1.4 billion people, and combined they make up more than a third of the world’s 8 billion people.

Not long ago, India wasn’t expected to become the most populous until later this decade. But the timing has been sped up by a drop in China’s fertility rate, with families having fewer children.

Today, China has an aging population with stagnant growth despite the government retreating from its one-child policy seven years ago.

In contrast, India has a much younger population, a higher fertility rate, and has seen a decrease in infant mortality over the last three decades.

Still, the country’s fertility rate has been steadily falling, from over five births per woman in 1960 to just over two in 2020, according to World Bank data.

India's continued growth is likely to have social and economic consequences. India has the largest number of young people at 254 million aged between 15-24 years, according to the U.N.

Experts hope this means an expanding labor force that can help fuel growth in the country for decades to come. But they warn it could just as swiftly become a demographic liability if the growing number of young people in India are not adequately employed.