How Do Birth And Death Rates Shape Population Change?
- Population change isn't random.
- Over time, many countries experience a broadly similar shift from high birth rates and high death rates to low birth rates and low death rates.
- The demographic transition model (DTM) is a simplified way to describe this pattern and to think about its impacts on people, services, and economies.
Demographic Transition Model (DTM)
The demographic transition model (DTM) is a theoretical framework that describes population change over time through distinct stages of development. It examines the relationship between birth rates, death rates, and overall population growth as a country develops economically and socially.
Birth Rate
The number of live births per 1000 people per year.
Death Rate
The number of deaths per 1000 people per year.
Natural increase
Natural increase is the difference between the crude birth rate (CBR) and the crude death rate (CDR), expressed as a percentage.
In many data tables you will also see rate of population growth (%), which includes natural increase plus the effects of net migration (immigration minus emigration).
The Five Stages Show A Shift From Survival To Ageing
- The DTM has five stages.
- Countries often move through them as living conditions and development change, although the timing and exact path vary.
Stage 1: high birth rates and high death rates keeps population low
- In Stage 1, families tend to have many children, but many people die young. This produces a low, stable total population because births and deaths are both high.
- Typical reasons include limited medical care and sanitation, frequent disease outbreaks, unreliable food supply, and little access to contraception.
Stage 1 is like trying to fill a bucket that has a big hole. You pour in a lot of water (high births), but a lot leaks out (high deaths), so the water level (total population) stays low.
Stage 2: death rates fall first, so population grows rapidly
- In Stage 2, the death rate drops sharply while the birth rate stays high.
- The gap between births and deaths widens, creating high natural increase and rapid population growth.
- Common drivers include cleaner water and better sanitation, vaccination and basic healthcare, and improved food production and distribution.
- A common misconception is that rapid population growth in Stage 2 is caused by a sudden rise in births.
- In the DTM, it is mainly caused by fewer deaths, especially fewer child deaths.
Stage 3: birth rates fall, slowing growth
- In Stage 3, the birth rate begins to fall.
- The death rate is already low, so the gap between births and deaths narrows and growth slows.
- Reasons for falling birth rates often include:
- Improved education (especially for girls)
- More women in paid employment
- Access to contraception and family planning
- Urbanization (children become less economically useful for farm work)
- Lower infant mortality (so parents feel less need for "extra" births).
- Education links to many factors at once.
- Higher educational attainment can increase employment opportunities, raise income, improve health knowledge, and change family-size decisions. These factors are interrelated, not separate.
Stage 4: low birth rates and low death rates stabilize population
- In Stage 4, both birth and death rates are low, so natural increase is small and the total population is high but stable or slowly rising.
- In many classroom classifications, countries in Stage 4 are treated as more economically developed countries (MEDCs).
- Key features often include high life expectancy, widespread healthcare, and smaller family norms.
Stage 5: birth rates drop below death rates in ageing populations
- In Stage 5, the birth rate can fall below the death rate.
- The total population is high but may begin to decline because the population is ageing and fewer babies are born.
- Germany is often cited as a country in Stage 5, with a birth rate lower than its death rate.
Ageing Population
A population in which the average age is rising and a large proportion of people are in older age groups, usually because of low birth rates and higher life expectancy.
How Does Population Data Let You Compare Countries At Different Stages?
- Birth and death rates are usually expressed "per 1000 people".
- Using example national data:
- Germany: birth rate $\frac{10}{1000}$, death rate $\frac{12}{1000}$, so natural increase is $10-12=-2$ per 1000 (a natural decrease).
- Tanzania: birth rate $\frac{37}{1000}$, death rate $\frac{7}{1000}$, so natural increase is $37-7=30$ per 1000 (a high natural increase).
- If a country has:
- Low birth rate (around 10 to 12 per 1000)
- Low death rate (around 7 to 10 per 1000)
- Low total fertility rate (around 1.6 to 1.9)
- It is likely to be in Stage 4 or 5, depending on whether births are still above deaths.
Why Do More Developed Countries Have Higher Death Rates?
- It can seem surprising that some high-income countries have a higher death rate than some low-income countries.
- One key reason is age structure: if a country has a large older population, more people die each year even when healthcare is excellent.
- When comparing death rates, always ask: "Is the population older or younger?"
- Death rate is influenced by how many elderly people there are, not just the quality of healthcare.
What Do Different Pyramid Shapes Mean?
- By looking at the overall shape, you can infer several key demographic characteristics:
- A very triangular pyramid suggests a high birth rate, many young dependents, and lower life expectancy.
- A more barrel-shaped or rectangular pyramid suggests a falling birth rate and rising life expectancy (often seen in more developed countries).
- An upside-down pyramid (narrow base, wider top) suggests a very low birth rate and an ageing population.
Dependency ratio
The dependency ratio is a measure of the proportion of dependents (people under 15 and over 64) to the working-age population (15–64 years). It is calculated as:
- You do not need exact numbers to learn from a population pyramid.
- First, read the shape (base, sides, and top), then connect it to birth rates, life expectancy, and dependency.
Linking pyramids to DTM stages
- Population pyramids provide visual clues to DTM stages:
- Stage 2 often looks strongly triangular because births are high and many people are young.
- Stage 3 still has a wide base, but it begins to narrow as births fall.
- Stage 4 tends to be more rectangular, showing many people surviving into older age.
- Stage 5 can become top-heavy as older cohorts form a large share of the population.
- In an exam-style "describe" question, explicitly refer to:
- The base (birth rate),
- The sides (survival through working ages),
- The top (life expectancy),
- Any bulges or dents (past events such as baby booms or migration).
How Does The DTM Help Predict Opportunities And Challenges For Governments?
- Demographers use the DTM and population pyramids to make projections.
- Governments then plan services and policies for likely future needs.
Youthful populations create pressure but can build future growth
- Countries in Stage 2 or early Stage 3 often have high demand for schools, vaccinations, and child healthcare.
- They also need to create jobs for a rapidly growing workforce in the near future.
- If job creation cannot keep up, unemployment and social pressure may rise.
- If a large cohort enters the workforce and there are enough jobs and skills, a country may benefit from a demographic dividend.
South Korea (Late 20th Century)
- South Korea shows how demographic change can boost economic growth when conditions are right.
- Falling birth rates created a demographic window
- Improvements in healthcare and education led families to have fewer children.
- Over time, this reduced the number of dependents relative to adults.
- A large working-age population entered the labor force
- A high proportion of the population was able to work, while fewer children needed support.
- This increased productivity and household savings.
- Government policy turned population change into growth
- Heavy investment in education improved workforce skills.
- Export-led industrialisation created jobs in manufacturing and technology.
- Higher employment raised income per person.
Fewer dependents + more workers + strong education policy = rapid economic growth.
Ageing populations raise the cost of pensions and healthcare
- Countries in Stage 4 and especially Stage 5 face different issues, including:
- Rising healthcare demand for chronic diseases
- Pension costs
- Questions about retirement age
- Potential labor shortages and slower economic growth.
- These pressures can lead governments to consider policies such as:
- Raising retirement ages
- Encouraging later retirement
- Supporting childcare
- Allowing more immigration.
France And Pension Reform
- France has a high life expectancy and a growing elderly population, increasing pension and healthcare costs.
- To reduce long-term strain on public finances, the government announced a rise in the retirement age from 62 to 64.
- Economically, this aimed to:
- Leep people in work longer,
- Increase tax revenue,
- Reduce pension payouts.
- Socially and politically, the reform triggered mass protests and strikes, with millions opposing the change.
- Many workers argued that longer working lives were unfair, especially for physically demanding jobs.
- This shows the challenge of balancing different stakeholder interests when dealing with demographic pressures.
- The policy makes economic sense on paper, but it directly affects voters’ daily lives, creates social unrest, and slows or weakens reform through political pressure.
- An ageing population isn' only a "problem".
- Older people can contribute through work, volunteering, and caring roles, depending on health and policy choices.
- What is the specific cause of rapid population growth in Stage 2 of the Demographic Transition Model?
- Why do some high-income countries in Stage 5 have a higher death rate than lower-income countries in Stage 2?
- How does the shape of a population pyramid change as a country moves from Stage 2 (triangular) to Stage 4 (rectangular)?
- What is a demographic dividend, and what two conditions are needed for a country to benefit from it?