Look again at Figure 2.1, where you can see that stages 2 and 3 of the DT initially involve a rapid decline in death rates while birth rates remain high. Then, death rates decline as birth rates start to slow down. The two stages combined are associated with a rapid rise in total population. This occurred first in the global North, then, by the last half of the twentieth century, in the global South. In this chapter, we consider the dynamics and consequences of this expanding population.

DECLINING INFANT MORTALITY

A dramatic change resulted from the decline in infant and youth mortality. This is an important demographic variable because up until the mid-twentieth century, infant mortality rates were responsible for almost half of total mortality. Infant mortality measures those who died in their first year of life. Youth mortality measures those who died before reaching the age of 15. Throughout most of human history, almost half of newborns died in the first year of life, and for those that survived around 50 per cent died as youths. Today, the global infant mortality rate is 4.3 per cent and under 5 per cent for youth mortality. It is a staggering decrease and is a major reason for rapid population growth. Figure 4.1 depicts the rapid fall-off in rates in just one country, the UK.

There was a historical and geographical dimension to these fundamental demographic changes. The decline of child mortality occurred first in the global North in the late nineteenth and first half of the twentieth century, while it mainly took effect in the global South much later, in the final third of the twentieth century. Some statistics reveal these differences. Even as late as 1990, the child mortality rate in Burkina Faso was almost 19.8 per cent while it was only 1.2 per cent in the USA. But by 2017, Burkina Faso's rate was only 8.1 per cent and it was below 1 per cent in the USA

Newborn babies and youths are particularly vulnerable to a variety of diseases and ailments. But with adequate care and attention they can survive, and with improved survival rates the population can climb very quickly. The main reason behind the fall in infant mortality was the improvements in health and nutrition. We can look at just one example to stand in for many.