Population – Birth rate, Death rate, Migration

This is the total number of people (including children, the disabled, beggars and other persons) living within a geographical area or country at a particular time. The question of population gave rise to the need to conduct population census.

Determinants of Population Size and Growth

The following are the major factors determining the size and growth of population

  1. Birth Rate
  2. Death Rate
  3. Migration
  4. Religion
  5. Modern Medicine
  6. Birth Rate

This refers to the number of children born within a year out of every 1000 people in the country. Generally, birth rate is higher in West African countries than in the Western countries. Can you provide the reason for this?

Determinants of Birth Rate

(i) Age and sex distribution of the population: Females are more fertile than male, if the population of female in a particular country is more than the population of male, it increases the birth rate.

(ii) Family planning: The practice of family planning in a country reduces the birth rate.

(iii) The quality of medical services available: Improved medical services increase the birth rate.

(iv) The time of marriage (early marriage or late marriage): Early marriage increases the birth rate while late marriage reduces the birth rate.

(v) Educational pursuit: Educational pursuit reduces the birth rate.

  1. Death Rate

This refers to the number of people who die in the year out of every 1000 people of the population.  Just as birth rate is higher in West African Countries than industrialized countries, death rate is also higher.

Determinants of Death Rate

The death rate of a country can be influenced by the following:

(i) Occurrence of Natural Disasters: Natural disaster and epidemics in a country increase the death rate in that country.

(ii) Occurrence of domestic and external wars: Domestic and external wars in a particular country increase death rate in that country.

(iii) Composition of the age distribution: If the proportion of aged people in a country is very high, death rate will increase.

(iv) Level of per capita income and standard of living: If the living standard of people in a country is high, there will be increase in death rate.

(v) Medical and Health facilities available: If there are improved medical facilities in a country, death rate increases and vice versa.

  1. Migration

This means the movement of people in and out of a country. Migration has two components:

  1. Immigration: this is the movement of foreigners into a country.
  2. Emigration: this is the movement of people out of a country.

Factors Influencing Migration

The factors influencing migration are as follows:

(i) The quest for better welfare

(ii) The search for suitable climatic conditions

(iii) Problems of natural disasters such as floods, earthquake

(iv) Political instability which can cause insecurity of lives

  1. Religion

Owing to its respect for human life, Christianity discourages artificial birth control and abortion while Islam on the other hand encourages polygamy. These actions by religious bodies have led to increase in population.

  1. Modern Medicine

The use of modern medical facilities and the establishment of bodies like World Health Organization (WHO) have helped to reduce mortality rate.

Population Growth Rate

This is the rate at which the population of a country multiplies itself. It can be positive or negative.  It is calculated thus:

                                           Growth Rate = Birth rate – Death rate + Net Migration

On the other hand, natural growth rate is just the difference between the birth and death rates of a given population, i.e

                                                 Natural Growth rate = Birth Rate – Death Rate

Net Migration

This is the difference in the flow of people into and out of a country. In other words, it is Immigration minus emigration.


The population of Nigeria in 1970 was 60m. From 1971-1975, the total number of birth was 25m and deaths stood at 3m.  8m immigrants and 4m emigrants were recorded.  You are required to

  1. Determine the net migration
  2. Calculate the population of the country in 1975
  3. What is the percentage growth rate in 1975?


  1. Net Migration = Immigrants  – Emigrants

= 8 million – 4milllion

= 4 million

  1. Growth Rate:

= Birth rate – death rate + net migration

= 25m – 3m + 4m

= 26million

The population of Nigeria in 1975 = 60million + 26million

= 86million.

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