India's population has jumped to 1.21 billion in 2011 from 1.02 billion in 2001, according to new census data. This rise in the population has made India more populous than Indonesia, United States, Brazil, Pakistan and Bangladesh combined.
The nation's cultural preference for male children continues to shape the population.The child sex ratio in the country declined to 914 females to 1,000 males, the lowest figures since 1947, the data recorded.
Sex selective abortion based on ultrasound scans is illegal in India but mothers come under huge pressure to produce male heirs who are seen as wage-earners and future family leaders.
Equality campaigners say the imbalance is due in part to unwanted daughters, who are often considered financial burdens, being neglected after birth.
The issue of "gendercide" is one of the most contentious social problems in Asia, where the United Nations says millions of women are effectively missing from the population.
India started its 2011 census in April last year, with 2.5 million officials travelling across the nation to reach more than 600,000 villages and 7,000 towns and cities.
Final census figures are expected to be released later this year.
Last month China said that its population -- already the world's largest -- increased by 6.3 million last year to hit 1.341 billion by the end of 2010.