India's average total fertility rate (TFR) in 2015 was 2.3, a decline from 2.5 in 2010. TFR is the total number of children born or likely to be born to a woman in her lifetime if she were subject to the prevailing rate of age-specific fertility in the population.

India's TFR is now 2.2, and the government has said it is likely to achieve the target of 2.1 by the end of 2017.

A TFR of about 2.1 children per woman is called replacement-level fertility, which means a population that is stable, neither rising nor falling.

The ministry of health has identified seven states--Assam, Bihar, Chhattisgarh, Jharkhand, Madhya Pradesh, Rajasthan and Uttar Pradesh--with high TFR. These states are home to 534.8 million people, or 44.2% of India's population, according to 2011 Census data. Within these states, 145 districts have been selected for action to reduce TFR to 2.1 by 2025 while the India average of 2.1 will, according to the government, be achieved by the end of 2017.

However, achieving the replacement rate does not mean population will stabilise. It will keep growing because replacement level fertility will lead to zero population growth only if mortality rates are constant and migration also has no net effect. Past momentum and current demographic trends also take several generations to settle.

A change to replacement level fertility will lead to a stable population only in the long run. India's population is projected to increase to 1.6 billion by 2050, by which time it will be the most populous country in the world, according to estimates by the United Nations.

Some ways identified by the government for reducing TFR include making contraceptives available, reducing the proportion of young mothers and providing family planning kits.

States With High Total Fertility Rate In India, 2015

Source: Ministry of health and family welfare, Census (2011)

(Patil is an analyst with IndiaSpend.)