Up until 1976, seats in the Lok Sabha, Rajya Sabha, and state assemblies were reallocated to maintain nearly equal population representation. But the 42nd Amendment froze the number of seats until the 2001 Census.
https://theprint.in/opinion/delimitation-in-india-north-vs-south/2589801/
The 50-year freeze on the delimitation of parliamentary constituencies—initiated during the Emergency in 1976 for an initial 25-year period—has now snowballed into an acrimonious debate between the South and the North. As scholar Ravi K Mishra’s recent book Demography, Representation and Delimitation shows, the current discourse is riddled with factoids overshadowing facts.
Multiple issues—ranging from intra-state equity and parity among Lok Sabha MPs to the Finance Commission’s population-based fund devolution—have been collapsed into one, posing a serious challenge to building consensus on this contentious issue.