The southern states seem to be reversing course on population policy. After decades of limiting family size, residents are being urged to have more children. Andhra Pradesh has proposed cash incentives for having a third and fourth child. Tamil Nadu has extended regular maternity benefits to all female government employees having a third child.  Telangana has removed previous restrictions that barred persons having more than two children from contesting elections. This shift is partly driven by political motives – states with lower populations risk having lower representation in Parliament. But the underlying reasons that have triggered panic among politicians are purely demographic, and reflect many years of changing patterns of birth, death and fertility.

Most demographic discussions begin and end with the total fertility ratio, or TFR, or the average number of children a woman has in her lifetime. It is well known that India’s fertility rate is falling and is below the replacement rate (approximately 2.1) in many states. However, TFR, while important, is only one driver of population growth. Future population growth depends on four sets of factors: age-structure of population, fertility, mortality and migration. Fertility has a positive impact on population when it is higher than the replacement rate.  Falling mortality – as reflected in more infants surviving to adulthood or adults living longer – supports population growth. Outmigration reduces population, in-migration increases it; the net impact depends on which is higher. Finally, the current age structure decides future birth and death trends. A predominantly young population is more likely to have children and contribute to population growth; an ageing one cannot do so.

To understand the demographic disadvantage faced by the southern states, it is useful to compare them against northern states with the highest TFRs, namely, Uttar Pradesh, Madhya Pradesh, Rajasthan and Bihar. These four states can be considered as being their opposites in terms of fertility, and hence least likely to encourage their residents to have more children. To start with, the two groups have starkly different current population structures. Keralam is the oldest state with median age at nearly 40 years; and nearly one-fifth of its population is elderly. At the other extreme is Bihar – the youngest state with median age of 28 years – where only 8.5% of the population is estimated to be 60 years or older. Other states lie somewhere between these two. There is a distinct north-south divide: the population of southern states bulge at the older end; the northern ones have a greater share of children.

Across India, the common trend is that fewer kids are being born and people are living longer. However, this trend is far more pronounced in the south. The southern states are uniformly below replacement TFRs, while the northern ones are well above their replacement rates. Using life expectancy as a summary indicator of mortality; it is seen that the southern states, especially Kerala, have relatively higher life expectancy.

To estimate future population, demographers start with the current population structure and apply projected fertility, mortality and migration rates to it. This is the point at which the disadvantages faced by the south become obvious. First, the south has a lower share of children in its population, so in two decades time, there will be a smaller pool of women of reproductive age, which means a smaller pool of potential mothers. Second, fertility rates in the south are already much lower than the north; so the next generation of women in the south are likely to have fewer babies than their northern peers. That’s a double whammy: and data shows how it will play out. Using projections of the Population Foundation of India, by 2046, the population of those under 15 years in the southern states is expected to drop to 12-15% of the total. This is comparable to the current population share of under-15-year-olds in advanced European countries!

The situation appears worse when we compare absolute number of births because the southern states have comparatively lower population. In 2026, the four selected northern states had 3.9 times as many annual births as the southern states; by 2051, the ratio is projected to rise to 4.2. Both groups are expected to have fewer births in this period, but the fall is sharper for the south Indian states.

These results justify, to some extent, the urgency demonstrated by the leaders of Tamil Nadu and Andhra Pradesh in adopting a child-friendly stance. As countries around the world have discovered, there are only two ways to combat the problem of declining population growth – encourage inward migration, or encourage couples to have more babies. Southern states already receive a large number of in-migrants from labour surplus north Indian states. According to Census data, Andhra and Tamil Nadu top the list with 3.7 million and 3.4 million inward migrant workers respectively; and these numbers are expected to rise as their local population ages or migrates to foreign shores. However, inward migrant workers do not usually replace those migrating out from the southern states. One reason is that the nature of jobs done by migrant workers does not encourage permanent residence. The south India interstate migration survey 2026 showed that 61-75% of employment in key migration-heavy sectors was temporary in nature. 

Not surprisingly, having more children seems to be the only way to boost population. The experience of other countries shows that it is notoriously difficult to raise the fertility rate. South India cannot expect a three- or even two-child family to become the new norm. The best it can hope for is to achieve a small but sustained rise in fertility. Even if TFR remains below the replacement rate, an increase (say from 1.5 to 1.8) would alter the population structure in a meaningful way, and help the southern states manage some of their demographic challenges.