India is world's second largest populated country after China. As per 2011 census India's population stands at more than 121 crores. It increased at a rate of 1.03 percent during 1990-2001.
The main cause of fast rise in India's population is the sharp decline in death rate while the birth rate has not decreased as fast.
Death rate is defined as the number of people died per thousand of population while birth rate is defined as the number of people taking birth per thousand of population.
In 2010, the birth rate was 22.1 persons per one thousand population while the death rate was only 7.2 persons per one thousand population. Low death rate is not a problem. In fact it is a sign of development. Low death rate reflects better public health system.
But high birth rate is a problem because it directly pushes the growth of population. After 1921, India's population increased very fast because birth rate declined very slowly while death rate declined very fast. From 49 in 1921 the birth rate declined to 22.1 in 2010 while during the same time period, death rate declined from 49 to 7.2.
Hence the population growth was very rapid in India. Heavy population pressure has become a major source of worry for India. It has put burden on the public exchequer to mobilize enough resources to provide public education, health care, infrastructure, etc.