Fertility, Mortality and Migration

People are born, people move, and people die. Not to be too morbid (there's a lot more to life in between!), but these three things we can be sure everyone does. In fact, on a global scale, these three things can show us fascinating trends in society and the ever-changing makeup of humanity that all of us are part of. In this explanation, we will look at how fertility, mortality, and migration change our world.

Fertility, Mortality, and Migration Demography

Fertility, mortality, and migration determine the population of a country. These three factors can give us insight into where a population is heading, how developed the country is, how the economy is doing, and how desirable of a place it is to live. Through these demographic indicators, we can even explain many cultural, economic, and political issues countries may be facing.

Demographic Forecasting of Mortality, Fertility, Migration, and Population Data

The global population is expected to hit 8 billion in 2022. Where will most of those people be born? Many will be born in less developed countries in Asia and Africa. While these countries experience exponential population growth, many highly economically-developed countries are starting to see a decline in population. Why might this be? As countries develop economically, mortality rates decline as the quality of life rises, but fertility rates also start to fall. This is often due to a range of social and economic factors.

Fig. 1 - World Population Projection Pyramid

Furthermore, the more a country develops, generally the more attractive it is to live there, More immigrants will migrate there, and fewer emigrants will leave. People living longer and not as many being born in the country, and more people moving to the country from elsewhere leads to shifts in the demographic makeup of a country. Demographics are everchanging, and they can explain many things in our world, from economics to political issues, by looking at the cultural and generational distribution of the people who make up the country.

A good model for seeing the basic format countries follow on the path of development is the democratic transition model.

Fig. 2 - The Demographic Transition Model

The demographic transition model shows five stages of how a population may evolve over time in terms of the proportion of the population in each age group. A country moves into the next stage of this model through economic development.

The five blue and pink graphs at the bottom are representative population pyramids of how one might expect the distribution of age of the population to look at each stage. Men are represented in blue, and women in pink. The graphs show the population of young people at the bottom and older people at the top. We can see in the first pre-industrial stage a large youth population and a very small elderly population. As a country moves through the stages over the course of decades or even centuries, the age of the population starts to even out, then may even become top-heavy as fertility rates drop.

The fifth and final stage is about the future projections of fertility rates. It is possible that fertility rates may pick up again as countries recognize the issues of population decline and enact policies to ease the burden of balancing a career with the high time and monetary expense of raising children. For example, affordable child care or government services can increase fertility.

Fertility Definition

Fertility, in its simplest definition, is the ability to have children.

Regarding demography, we will refer to fertility as the fertility rate, how many children, on average, a woman will have in her lifetime. Fertility rates are based on four factors: favorable social norms, flexible labor markets, cooperative fathers, and family policies.¹

Favorable social norms typically involve flexibility in traditional gender roles to fit mothers who want to have a family and a career.

Flexible labor markets can mean not having repercussions for taking a career break to start a family. Tight labor markets are favorable, meaning jobs are plentiful, as high unemployment can make those employed hesitant to cut back on work or quit to focus more on their family.

Cooperative fathers are the next factor. Traditionally, the woman had the majority role in raising children. When the duties of raising children are split more equally, fertility rates can increase as women are better able to balance careers with raising a family.

Family policies can have an impact on publicly available child care and can ease raising children for fathers and mothers, thereby increasing their ability to raise more children.

Falling mortality rates can be explained by greater access to nutrition, medicine, and public health. Falling birth rates are due to economic incentives.³

Mortality Definition

Mortality is being subjected to death, as all living things are.

Regarding population studies, mortality discusses how many people in a country die each year. When countries are able to develop and grow peacefully, people gain access to better healthcare, and goods and services become more available through large economies with global reach. This allows the quality of life to increase as well as life expectancy, and not as many children are dying before the age of one, lowering the infant mortality rate. If most people live longer, then the mortality rate will be lower. In the demographic transition model, we see that the mortality rate starts decreasing as the main indicator of shifting from stage one to stage two. It can be several decades before fertility rates start to decrease as well.

In low-income countries, neonatal conditions are the leading cause of death, whereas they are not even in the top 10 in high-income countries. This can be reflected in mortality rates as low-income countries have an infant mortality rate of 47 per 1,000 live births compared with high-income countries have an infant mortality rate of less than a tenth of low-income countries at 4 per 1,000 live births.³

Other high causes of death in undeveloped, low-income countries that are almost nonexistent in high-income countries are death from diarrheal disease or viruses, mostly due to unsafe drinking water; inadequate sanitation services; and poor hygiene conditions. Malaria is a common cause of death in low-income countries but is relatively preventable or treatable when there is access to healthcare services.⁴

Migration Definition

Migration can be split into two components: emigration and immigration.

Emigration is people leaving a country. People will leave a country for many reasons. Some of these reasons might be to search for better work opportunities; conflict; natural disasters; family ties; to make money to send remittances back to their home countries; and a host of others. Usually, less developed countries experience more emigration than developed countries. However, certain factors, such as oppression, corruption, or lack of freedom, can be push factors in more developed countries as well.

Immigration is people moving to a country. Often the opposite is true here; developed countries experience more immigration than less developed countries because they have more desirable standards of living, quality of life, better access to education, and often, but not always, more freedom, liberty, and less corruption.

Immigration can often be a tool for countries to continue economic and population growth when they move into the later stages of the demographic transition model. When a country is developed, the average age typically increases, and the fertility rates decline, which can lead to stagnant economic growth and labor shortages as fewer and fewer people enter the workforce. Immigration can often be an economic boost to a country facing these challenges; however, immigration often comes with shifting and diversified cultural identities that can be met with social resistance.

Factors affecting Population Growth, Fertility, Mortality, and Migration

Factors affecting the demographic makeup of a society can be a country's level of development, health care services, access to goods and services of an industrialized economy, and in the later stages, the balance that people have between career and time to raise a family.

Fig. 3 - Average Population Change by Country

The following table looks deeper at what we can infer from looking at population factors: