Conversely, with fertility below replacement, a large elderly generation eventually results (as in an aging "baby boom"); but since that generation failed to replace itself during its fertile years, a subsequent "population bust", or decrease in population, will occur when the older generation dies off. This effect has been termed birth dearth. In addition, if a country's fertility is at replacement level, and has been that way for at least several decades (to stabilize its age distribution), then that country's population could still experience coincident growth due to continuously increasing life expectancy, even though the population growth is likely to be smaller than it would be from natural population increase.