Every argument about how Lok Sabha seats will be redrawn has relied on a consistent demographic premise. The northern states continue to have higher fertility rates, while southern states have achieved fertility decline earlier, and any population-based seat reallocation would benefit states who have slower progress in family planning (or high fertility rates) compared to those that have done well. This narrative has been widely cited by policymakers and commentators. That said, data from the recently released NFHS-6 (2023–24) provides new evidence that complicates this premise and have not yet been fully incorporated into the ongoing delimitation debate.A debate that has stalled, not settledThe 42nd Amendment of 1976 froze each state’s Lok Sabha seat count at its 1971 level, precisely so that states that brought fertility down early would not be penalised relative to those that didn’t. The 84th Amendment (2001) extended this freeze to the first census after 2026, and the 106th Amendment (2023), which introduced one-third reservation for women, tied its own start to a future delimitation. In April 2026, the government moved to resolve it all at once by introducing three linked bills – the Constitution (131st Amendment) Bill, the Delimitation Bill, and the Union Territories Laws (Amendment) Bill, which together would have expanded the Lok Sabha from 543 to 850 seats and reallocated them on the basis of the 2011 Census.This legislative effort did not succeed. A two-thirds majority is required for a constitutional amendment. The 131st Amendment Bill did not achieve this majority, as only 298 MPs supported it out of 528 members (present and voting), resulting in a shortfall of 54 votes. As a result, the government withdrew the remaining two bills. One of the objections raised by the opposition was the use of the 2011 Census for reallocation, citing that it would reduce representation from the southern and north-eastern states. The seat projections used here come from PRS Legislative Research, an independent not-for-profit group in Delhi that tracks legislation and parliamentary business. PRS calculated what each state’s Lok Sabha representation would look like if seats were allocated in proportion to its 2011 Census population, the basis the government’s own bills proposed. These are illustrative rather than official: no Delimitation Commission has been constituted, and the exercise, whenever it happens, would in practice use a later census. We use PRS’s constant-total scenario, which holds the Lok Sabha at its current strength, because it isolates the shift in each state’s share of the House rather than the effect of enlarging it.Table 1. Projected Lok Sabha seat change and total fertility rate, by stateStateSeat ChangeTFR(2011, Total unchanged)NFHS-5 → NFHS-6Uttar Pradesh +92.4 → 2.2 Bihar +6 3.0 → 2.7 Rajasthan +5 2.0 → 2.1 Madhya Pradesh +3 2.0 → 2.1 Maharashtra +2 1.7 → 1.8 Tamil Nadu −7 1.8 → 1.7 Kerala −5 1.8 → 1.8 Andhra Pradesh* −4 1.7 → 1.8 Odisha −2 1.8 → 1.7 Karnataka -11.7 → 1.8Himachal Pradesh-11.7 → 1.8Notes: Projected seat change under the 2011 Census with total Lok Sabha strength held constant (PRS Legislative Research); total fertility rate from NFHS-5 and NFHS-6. *Andhra Pradesh figure includes Telangana, as in the PRS table. What NFHS-6 actually showsThe states projected to gain the most seats are also those experiencing the most rapid declines in fertility. Uttar Pradesh’s total fertility rate decreased from 2.4 to 2.2 children per woman between the two survey rounds, while Bihar’s rate declined from 3.0 to 2.7, representing the largest reduction among major states. These two states are the principal beneficiaries of a population-based reallocation and are also those whose fertility rates are converging most rapidly toward the national average.On the other hand, multiple states which were projected to lose seats have reported an increase in their fertility rates. These states include Karnataka, Himachal Pradesh, and Andhra Pradesh. Each of these states saw a jump in its total fertility rate from 1.7 to 1.8. Kerala’s rate remains unchanged at 1.8. Tamil Nadu is the only southern state to record a further decline, from 1.8 to 1.7. The most recent data does not support the assumption of a persistent and widening fertility gap.Figure 1 – Three-panel: A) Fertility gaps are narrowing (TFR, NFHS-5 → NFHS-6, key states); B) Populations keep diverging (2011=100 population index through 2036, growth relative to each state’s own base); C) Share of India’s population (southern five states vs. UP vs. Bihar, 2011–2036, against southern seat share today of 23.8%). Sources: NFHS-5/6 fact sheets; NCP Technical Group (2020), Table 8.These findings should be interpreted with caution, as the estimates shown above are from a single round, and uses state-level data which could be subject to sampling issues, and a small change of 0.1 could also reflect statistical noise rather than a real change. However, the declines of 0.3 in Bihar and 0.2 in Uttar Pradesh align with patterns observed in fertility transitions across the world. The intersection in fertility rates is evident, although the precise rate remains uncertain.Why doesn’t this settle the argument?Although the reduced fertility gap might make it seem like worries about southern states’ representation are exaggerated, this view misses key demographic factors. Delimitation is based on the total population, not just fertility rates, and population size changes more slowly than fertility because of population momentum, which often takes a generation to show up.For decades, Uttar Pradesh and Bihar have had large young populations. Even though their fertility rates are now close to the national average, many women are just reaching childbearing age, so these states will keep growing for another two or three decades before lower fertility has its full effect. This matches United Nations projections. In contrast, Kerala, Tamil Nadu, and Andhra Pradesh reached low fertility earlier, so their populations are older and growing more slowly or have stabilised. Figure 2 – Population pyramids, 2011: Uttar Pradesh (129 girls aged 0–14 per 100 women aged 15–29), Bihar (161 per 100), Tamil Nadu (86 per 100), and Kerala (95 per 100). The wide youth base in UP and Bihar versus the older, more rectangular structure in Tamil Nadu and Kerala illustrates the built-in momentum each state carries forward. Source: Census 2011 smoothed population, NCP Technical Group (2020), Table 2.So, NFHS-6 data does not show a permanent or worsening gap, nor does it suggest the gap will close quickly as fertility rates come together. Instead, the differences built up over the last fifty years are only now starting to slow, and population differences that matter for seat allocation will persist for a while.Expanding the Lok Sabha does not resolve the underlying issueOne potential solution to the underlying issue is to increase the total number of Lok Sabha seats. This helps, as it ensures no state experiences a reduction in representation. The proposed 131st Amendment would have helped by expanding the House to 850 seats. However, PRS projections show that such an approach does not address the core concern: the relative share of seats for each state. The proportion of seats allocated to Uttar Pradesh and Kerala, for example, remains largely unchanged under both constant-total and expanded scenarios. Thus, increasing the size of the House alters the absolute seat counts but does not affect the regional balance of representation, which is the central issue.Another effect of increasing the Lok Sabha to 850 seats is that the Rajya Sabha would remain at 250 seats. This would change the ratio between the two Houses from about 2.2:1 to 3.3:1, which would reduce the Rajya Sabha’s influence, since it gives states more equal representation. For states worried about delimitation, having a larger Lok Sabha compared to the Rajya Sabha creates a similar problem for their representation.The gap that isn’t convergingAnother relevant trend concerns the likelihood of continued fertility convergence. Between NFHS-5 and NFHS-6, women’s educational attainment, which is the strongest predictor of long-term fertility decline, rose faster in the states PRS projects would lose seats (an average gain of roughly 7.5 percentage points in the share of women with ten or more years of schooling) than in the states projected to gain (roughly 4.9 points). This suggests that the structural factors driving fertility decline continue to favor states with already low fertility.This pattern has two main points. First, the recent small rises in fertility in Karnataka and Andhra Pradesh are probably just short-term changes, not a sign that the overall downward trend is reversing. Second, the declines in Bihar and Uttar Pradesh seem likely to persist, since they coincide with improved education for women, as in other places where fertility has fallen.The number the debate needsOver the past year, much of the discussion on delimitation has relied on NFHS-5 and earlier Sample Registration System data, without reassessing whether the underlying demographic assumptions remain valid. NFHS-6 does not fully invalidate these assumptions, but it indicates that they are less accurate than current political discourse suggests. By the time a Delimitation Commission is established and a census is selected, the relationship between the rate of fertility decline and actual population size in each state is likely to diverge further. This evolving gap, rather than the static assumptions of the present debate, will be central to future discussions on seat allocation.Karan Babbar is an Assistant Professor of Economics at XLRI Jamshedpur, and Raunak Maitra is a Master’s Student at the Centre for Development Studies, Thiruvananthapuram.Sources: Total fertility rates from NFHS-5 (2019–21) and NFHS-6 (2023–24) fact sheets. Seat projections and legislative detail from PRS Legislative Research, ‘The Constitution (131st Amendment) Bill, 2026’ and ‘The Delimitation Bill, 2026’; the seat column shown holds total Lok Sabha strength constant to isolate the shift in each state’s share. Vote figures from Lok Sabha proceedings, 17 April 2026. Andhra Pradesh figures include Telangana, and Jammu & Kashmir includes Ladakh, following the PRS table.