Elon Musk has drawn attention to India’s declining fertility rate after recent data showed the country’s Total Fertility Rate (TFR) has fallen below the replacement level.Responding to data shared by AF Post on X, The Tesla and SpaceX CEO Musk wrote, “India’s birth rate has fallen below replacement. Among those most educated, India’s birth rate fell below replacement many years ago.”Musk was reacting to a report highlighting India’s rapidly declining fertility levels.India’s fertility rate falls below replacement levelAccording to the 2024 Sample Registration System (SRS) report, India’s Total Fertility Rate has declined from 2.1 to 1.9 children per woman, pushing most states below the replacement fertility level of 2.1.The replacement level refers to the average number of children each woman needs to have for a population to replace itself from one generation to the next without migration.The SRS report found that only six states, Bihar, Uttar Pradesh, Madhya Pradesh, Rajasthan, Chhattisgarh and Jharkhand, continue to record fertility rates above the replacement level.At the other end of the spectrum, Delhi reported the country’s lowest TFR at 1.2 births per woman.What replacement fertility meansDemographers consider a TFR of 2.1 as the benchmark required to maintain a stable population size over time.When fertility remains below this level for prolonged periods, population growth slows and can eventually turn negative.Experts say this can lead to challenges such as an ageing population, a shrinking workforce and increased pressure on social welfare systems.UNFPA highlights demographic transitionThe trend was also highlighted in the United Nations Population Fund’s (UNFPA) 2025 State of World Population Report, which placed India’s fertility rate at 1.9 births per woman, below the replacement level of 2.1.While India remains the world’s most populous nation with more than 1.46 billion people, the latest data suggests the country is entering a new phase of demographic transition marked by smaller family sizes and slower population growth.Birth rate vs fertility rate: What’s the difference?Birth rate measures the number of live births per 1,000 people in a population each year. Total Fertility Rate (TFR) measures the average number of children a woman is expected to have during her lifetime.The two indicators are closely linked. A sustained decline in fertility rates generally leads to lower birth rates over time, which can eventually slow population growth and contribute to an ageing population.