The elements/factors responsible for population growth or change in size of population are as follows
(i) High birth rate and low death rate In India, after independence there was high birth and high death rate. However, the death rate has declined now considerably but the birth rate continues to remain high.
(ii) Child marriage Early marriages are common in many parts of India due to which more percentage of girls are married in the age group of 15-20 years. This results in giving birth to more number of children.
(iii) Illiteracy Still a large population of India is illiterate. Illiterate persons fail to understand the importance of family planning or the advantage of having a small family.