Do you mean in terms of demographic pyramid? Lets say that the average number of surviving children per couple is 2, then 4, then 2 again. The children/parents

Do you mean in terms of demographic pyramid? Lets say that the average number of surviving children per couple is 2, then 4, then 2 again. The children/parents ratio for the 2nd/1st generation is 4/2=2. The next generation is 2/2=1. Assuming that the average number of surviving children was about 2 per couple before all this, then the ratio basically returns to normal. The only abnormal ratio is the large generation compared to the previous one. After the large generation, the population is just bigger. But the gen1/gen2 ratio is normal. The population doesn't shrink back down to pre-boom levels.