2. In some countries, a low birth rate may actually be a problem. In Italy, for instance, women have on average 1.2 children -- well below replacement level, CBS News correspondent Mo Rocca reported.
Cohen said, "Some people think it is a big problem because it means that the population is aging rapidly. The aging population means there will be fewer young people to support the elderly in their old age, if the elderly retire, for example."
So unless Italians seriously reconsider their immigration policies or raise their retirement age, Mo Rocca said, "Well, they better get busy."
World population: Seven billion and counting
Special section: Eye on Parenting
"7 billionth" babies celebrated worldwide