The United Nations currently predicts that by 2027, India will overtake China as the world’s most populous country. Estimates suggest India and Nigeria will together add 470 million people in the next three decades — almost a quarter of the world’s population increase to 2050. In many parts of India, for instance, the total fertility rate — the expected average number of children born to each woman — is already well below the replacement rate of 2.1 and dropping faster than expected.
South Asia, for example, would have 600 million fewer people in 2100 than previously predicted thanks to lower-than-expected levels of fertility. Instead of growing throughout, India’s population would peak in 2050 and then decline to 70% of that number by the end of the century.