Step 1: Understanding the Concept:
The Demographic Transition Theory (DTT) explains the historical shift from high birth rates and high infant mortality rates in societies with minimal technology, education (especially of women), and economic development, to low birth rates and low death rates in societies with advanced technology and economic development.
The theory generally follows four stages:
1. First Stage: High Birth Rate (BR) and High Death Rate (DR), resulting in a low, stable population growth. This is typical of pre-industrial agrarian societies.
2. Second Stage: High BR and declining DR due to better healthcare, leading to a "population explosion."
3. Third Stage: Falling BR and low DR, leading to slowing population growth.
4. Fourth Stage: Low BR and low DR, leading to a stable or even declining population.
Step 2: Detailed Explanation:
For several decades post-independence, India was in the Second Stage (1951-1981) and then moved into the Third Stage.
The year 1921 is known as the "Year of Great Divide" because it was the last time India saw a negative population growth; thereafter, it entered the second stage.
Recent data from the National Family Health Survey-5 (NFHS-5) and the 2021-2022 projections indicate a paradigm shift.
The Total Fertility Rate (TFR), which is the average number of children born to a woman, has fallen to 2.0.
This is below the "Replacement Level Fertility" of 2.1, which is the rate at which a population exactly replaces itself from one generation to the next.
When TFR stays below 2.1 for a sustained period, the birth rate drops significantly. Combined with already low death rates achieved through modern medicine, the country moves into the Fourth Stage.
In this stage, the population growth rate stabilizes at a very low level.
India's entry into the fourth stage after 2021 implies that the country is moving towards demographic maturity, which brings about a "demographic dividend" where the working-age population is large relative to dependents, though it eventually leads to an aging population.
Step 3: Final Answer:
India is considered to have entered the Fourth stage of demographic transition after 2021 due to the TFR falling below the replacement level of 2.1.