Discuss the causes of high rates of population growth.

Worldwide, average family size is currently just under three children, higher than the two-child "replacement level" which would eventually result in stabilisation of population size. However, this global average does not illustrate the vast differences in average family size among regions. Most industrialised countries, such as Italy and Spain, now have an average family size of 1.1 to 1.3 children and are growing relatively slowly. Average family size in developing countries is more diverse, ranging from two children in a few countries to six or seven in many others.  This can be attributed to a variety of factors, such as the country’s religion, culture and economy.  In some cultures a large family is a sign of fertility and status and it is therefore desirable to have more children, which increases the birth rate and therefore the rate of population increase. In some cultures the male is also superior to the female, meaning that he decides on how large the family is, meaning that families are often large, again as a sign of fertility. In developing countries such as Malawi in South Africa, agriculture is still heavily relied on, especially at subsistence level.  This means that women do not have their own careers and traditionally their role is to bear and raise children, so they do not postpone having children in order to concentrate on their career, thus increasing birth rates.  The strong dependence on agriculture also means that a large labour force is required so people have more children in order to support themselves.  This results in high birth rates of 56.3 per 1000, much higher than replacement levels, meaning that the rate of population increase is also high at 35.7 per 1000 per annum.  Countries such as this, including Jordan and Pakistan, which have annual rates of increase at around 3% are likely to see their population size double by 2025.

The need for so many children to work to support a family at subsistence level means that a large proportion of the population is at the age where they should be in education, with 74% of Malawi’s population being below the age of 29.  Not only is there not enough facilities to support this amount of students, but many children are required to keep working to support their families, especially as bad weather and natural disasters such as cyclones and floods have devastated harvests, resulting in terrible food shortages.  For these reasons, just 3.4% of the population has received secondary and higher education, meaning that there are very few people qualified to provide healthcare and to provide information on things such as diet, vaccinations and contraception.  Simple things such provision of penicillin, influenza and typhoid vaccines and information on diarrhoea could increase life expectancy, meaning that people would be able to work for a longer period of their lives, resulting in a decrease in the need for children and lower rates of population increase.  Lack of information on balanced and healthy diets, especially in areas where only one crop is grown and in shorts supplies, means people do not know how to maintain good health and vitamin intake, resulting in a higher risk of illness which in turn means the death rate is high and people have more children to replace them, consequently increasing the rate of population growth.

However, widely available healthcare of a high standard can also result in high rates of population increase.  If the healthcare is of a high standard it means that less women have miscarriages and therefore more babies are carried for the full duration of the pregnancy and birth rates can remain high.  It also means that more diseases can be fought and life expectancy is increased, resulting in low death rates. When high birth rates and low death rates are combined, the result is a high rate of population increase, as more people are born than are necessary to replace those that have died.  Low death rates primarily reflect improved child survival rates and low infant mortality rates, and these are key determinants in family size, as life expectancy is increasing. This means that populations will tend to be ageing populations and women have a longer fertility period in which they can have children, typically between the ages of 15 and 50.  This results in population momentum as women are living throughout their fertility period and are having more children during this time, even where birth rates are low, as even when average family size is slightly higher than two children, the population will continue to grow.  Even if average family size worldwide were to reduce immediately to two children, world population would still increase to nearly 8.4 billion in 2050, because of the built-in momentum generated by the largest group of young people ever who are just beginning to enter their childbearing years. Despite increases in contraceptive use, the need for family planning is still growing. Because of the young age structure in developing countries, the number of women entering their childbearing years is increasing at a more rapid rate than the population as a whole, at about two percent, or almost 24 million women, a year.

Demographic experts believe that the shift from high to low birth rates and from low to high life expectancy, resulting in lower rates of population increase, is brought about by "social modernisation." This involves improved healthcare and access to family planning; higher educational attainment, especially among women; economic growth and rising per capita income levels; and urbanization and growing employment opportunities. Stabilisation of the world’s population will therefore depend on continuing or accelerating socio-economic development in the vast majority of the world’s developing countries. A number of factors could hinder the demographic transition, including declining economic growth, persistent poverty, or cultural factors that encourage large family size despite rising prosperity. If the transition were stalled, global population would most probably continue to rise throughout the next century, meaning that world population in 2050 could number anywhere between 8.1 billion and almost 12 billion.