there are two results of a birthrate that is too low to maintain a population. the first is that ultimately without the arrival of immigrants the population will decline.in over 20 countries the population is already in decline including Russia ukraing and japan. in other countries such as south Korea it soon will be Given present trends Ethiopia will have a larger population than Russia or japan by 2050. the second and more troubling result is population aging.Fewer and fewer young taxpayers will be supporting more and more old people. This will place even more pressure on the young to limit family size.If there are too few workers this will cause economic decline.