The following is academic writing. Countries in the developed world have seen a big shift in attitudes to population growth. Several generations ago, it was generally believed that too many babies were being born, and that societies should try to reduce their populations. Nowadays, however, the concern is the reverse - that birthrates are falling too low and that urgent action is needed to encourage people to have more children. But what are the causes of this trend? And how much are the attitudes and lifestyles of young people to blame? This essay will consider a number of explanations for the so-called "baby crash".