Reasons why birth rates, death rates and net migration rates can vary between countries

Economic Development – Population

Learning objective

Explain the reasons why birth rates, death rates and net migration rates can vary between countries and assess the consequences of these variations for economic development.

5.3.1 Key definitions (Cambridge 5.3)

Note: These are crude rates (total births or deaths divided by the total population). Age‑specific rates are used in more detailed demographic work but are not required for the IGCSE.

Cross‑cutting influences on all three rates

• Urbanisation – high housing costs and limited space tend to lower birth rates, increase pull‑factors for migration and can improve access to health services, reducing death rates.
• Cultural & religious norms – pro‑natal traditions raise birth rates; attitudes toward gender roles affect migration decisions.
• Government policies – family‑planning programmes, pro‑natal incentives or immigration controls can raise or lower any of the three rates.

5.3.1 Factors that affect the birth rate

• Economic development – higher income and lower child‑rearing costs lead to smaller families (↓ BR).
  Example: Japan (low BR) vs. Niger (high BR).
• Female education – schooling delays marriage and child‑bearing and increases knowledge of contraception (↓ BR).
• Access to contraception & family‑planning services – reduces unintended pregnancies (↓ BR).
• Cultural & religious norms – pronatalist values or religious teachings encourage larger families (↑ BR).
• Urbanisation – high housing costs, limited space and greater female employment discourage large families (↓ BR).
• Government policies
  • Pro‑natal incentives (tax breaks, child allowances) → ↑ BR (e.g., France’s family‑benefit system).
  • Restrictive policies (e.g., China’s former one‑child policy) → ↓ BR.

5.3.1 Factors that affect the death rate

• Healthcare quality & accessibility – better services lower infant and adult mortality (↓ DR).
• Nutrition, water & sanitation – adequate food, clean water and safe housing reduce disease (↓ DR).
• Prevalence of disease
  • High rates of communicable diseases (malaria, HIV/AIDS) increase DR.
  • Effective vaccination programmes decrease DR.
• Age structure – a larger proportion of elderly people naturally raises DR.
• Environmental & occupational hazards – pollution, natural disasters and dangerous work conditions raise DR.
• Public safety & conflict – war, crime and road‑traffic accidents increase DR.
• Government health policies – universal health coverage or lack thereof can respectively lower or raise DR.

5.3.1 Factors that affect the net migration rate

Migration is driven by push factors (conditions that encourage people to leave) and pull factors (conditions that attract people to move in).

5.3.2 Population structure, optimal size and economic consequences

• Optimal population – the size at which a country can provide a satisfactory standard of living for its citizens. It is not a fixed number; it depends on resource base, technology and institutional capacity.
• Dependency ratio – proportion of non‑working (young + elderly) people to the working‑age population. A high ratio raises the burden on the labour force.
• Demographic dividend – when a country has a large proportion of working‑age people and relatively few dependents, savings and productivity can rise, stimulating economic growth (e.g., East Asian economies in the 1990s).
• Ageing societies – a high proportion of elderly increases health‑care and pension costs, can reduce labour supply and slow growth (e.g., Japan, Italy).
• Consequences for development
  • Rapid population growth (high BR, high DR) → pressure on education, health, housing and natural resources → lower per‑capita GDP and higher poverty rates (e.g., Niger).
  • Very low birth rates (e.g., Italy) → shrinking labour force, higher dependency ratio, need for immigration to sustain growth.

5.3.3 Why population matters for living standards

• High birth rates can dilute income, reduce per‑capita GDP and lower Human Development Index (HDI) scores if resources are scarce.
• Low birth rates coupled with ageing increase per‑capita health and pension expenditures, potentially reducing disposable income for the working population.
• Net migration can raise or lower living standards:
  • In‑migration of skilled workers can boost productivity and raise GDP per head.
  • Large influxes of low‑skill migrants may strain public services if not managed.

Comparative summary of the main factors

Population‑change formula (Cambridge 5.3.2)

The overall change in a country’s population in a year is:

• ΔP = change in population
• B = number of births (birth rate × total population)
• D = number of deaths (death rate × total population)
• M = net migration (immigrants – emigrants)

Suggested revision diagrams

• Population pyramids – compare a high‑birth‑rate, high‑death‑rate country (e.g., Niger) with a low‑birth‑rate, low‑death‑rate country (e.g., Japan).
• Migration flow arrows – illustrate typical push arrows away from low‑income, conflict‑prone regions and pull arrows toward high‑income, stable nations.
• Dependency‑ratio bar chart – show how a youthful, a balanced, and an ageing population differ in the proportion of dependents to workers.
• Line graph of the demographic dividend – plot economic growth against the proportion of working‑age population.