The Fertility Divergence — The Central Driver
| State | TFR (2023 est.) | Year Reached Replacement | Population Growth Since 1971 | Demographic Status |
|---|---|---|---|---|
| Kerala | 1.5 | 1988 | 67% | Ageing — below replacement 35+ years |
| Tamil Nadu | 1.5 | 1993 | 90% | Ageing — below replacement 30+ years |
| Andhra Pradesh | 1.6 | 2004 | 95% | Ageing — below replacement 20+ years |
| Telangana | 1.6 | 2004 | 95% | Ageing — below replacement 20+ years |
| Karnataka | 1.7 | 2008 | 131% | Approaching ageing |
| West Bengal | 1.6 | 2005 | 72% | Ageing |
| Maharashtra | 1.7 | 2010 | 112% | Approaching ageing |
| Uttar Pradesh | 2.35 | ~2025 (proj.) | 175% | Peak momentum — fertility declining rapidly |
| Bihar | 2.98 | 2039 (proj.) | 195% | High momentum — fertility declining |
| National Average | 1.9 | 2025 | 155% | Below replacement nationally |
Sources: NFHS-5 (2019–21) [@cite_nfhs_5_2021]; SRS Annual Statistical Reports; Data for India (2025) [@cite_data_for_india_fertility]; CASI Demographic Dilemmas Series (2025) [@cite_casi_demographic_part1; @cite_casi_demographic_part2].
This is not a "north grew faster, south grew slower" gradient. It is a structural divergence in the timing of demographic transition — and a freeze that encoded one census moment of that divergence into the parliamentary map for fifty years.