Population Growth: Births, Deaths and Growth Rates – Population and Settlement (Senior 1 Geography) | Ganzaa

Population and Settlement

Lessons

Senior 1 · Geography

Population and Settlement

5 lessons

Lesson 3 of 5

Population Growth: Births, Deaths and Growth Rates

24 min

From 4.8 million to 13.2 million

Figure 1 shows Rwanda's population at each of its five censuses. The line climbs almost all the way, but not at the same speed. Find the flattest part of the line. Which years does it cover, and what might have slowed the growth?

Figure 1. Rwanda's population at each census, 1978–2022. Drawn by Ganzaa from NISR's Census 2022 report, Table 4.

What makes a population grow or shrink

A population changes in only three ways: people are born, people die, and people move in or out. Growth from births and deaths alone is called natural increase; lesson 5 deals with migration.

Definition

Birth rate (crude birth rate): the number of live births in a year for every 1,000 people in the population. $\text{birth rate} = \frac{\text{births in a year}}{\text{population}} \times 1\,000$ . Example: Rwanda's was about 27 per 1,000 in 2022.

Definition

Fertility rate: a measure of how many children women have. The total fertility rate (TFR) is the average number of children a woman would have in her lifetime at present rates. Example: Rwanda's TFR in 2022 was 3.6 children per woman.

Definition

Death rate (crude death rate): the number of deaths in a year for every 1,000 people in the population. Example: Rwanda's fell from 17.1 per 1,000 in 1978 to 6.3 per 1,000 in 2022.

Definition

Infant mortality rate: the number of babies who die before their first birthday for every 1,000 live births in a year. It is one of the best measures of a country's health care. Example: about 29 per 1,000 live births in Rwanda in 2022, down from 144 in 1978.

Definition

Natural increase and growth rate: natural increase is the birth rate minus the death rate; divided by 10, it gives a percentage. The growth rate also includes migration: it is the percentage by which the whole population grows in a year. Example: Rwanda grew by an average of 2.3% a year between 2012 and 2022.

Rwanda's population indicators

Indicator	Rwanda, 2022 census	Earlier comparison
Births in the previous 12 months	364,549
Birth rate (standardised, per 1,000 people)	27.4
Total fertility rate (children per woman)	3.6 (City of Kigali 3.0; Eastern Province 4.0)
Death rate (per 1,000 people)	6.3	17.1 in 1978
Infant mortality rate (per 1,000 live births)	28.9	144 in 1978
Life expectancy at birth	69.6 years	46 years in 1978; 64 in 2012
Average annual growth rate	2.3% (2012–2022)	2.6% (2002–2012)

Source: NISR, Census 2022 Main Indicators Report. The birth rate shown by NISR is standardised; it differs slightly from the simple calculation in worked example 1.

Worked example 1: calculating a birth rate

In the 12 months before the 2022 census, 364,549 babies were born in Rwanda, and the population was 13,246,394. Find the crude birth rate.

\text{birth rate} = \frac{364\,549}{13\,246\,394} \times 1\,000 \approx 27.5\ \text{per 1,000}

Answer. About 27.5 births for every 1,000 people, very close to NISR's standardised figure of 27.4.

Worked example 2: natural increase

Use NISR's birth rate (27.4 per 1,000) and death rate (6.3 per 1,000).

\text{natural increase} = 27.4 - 6.3 = 21.1\ \text{per 1,000}

\frac{21.1}{1\,000} \times 100 = 2.11\% \ \text{a year}

Answer. About 2.1% a year from births and deaths alone, close to the measured growth rate of 2.3%. (The two differ because the rates come from different years and methods, and because of migration.)

Worked example 3: growth between two censuses

The population was 10,515,973 in 2012 and 13,246,394 in 2022. Find the increase and the percentage increase.

13\,246\,394 - 10\,515\,973 = 2\,730\,421

\frac{2\,730\,421}{10\,515\,973} \times 100 \approx 26.0\%

Why is the yearly rate 2.3%, not 26 ÷ 10 = 2.6%? Growth builds on itself, like interest on savings: each year's new people are added to a bigger total. Growing 2.3% a year for ten years gives

1.023^{10} \approx 1.255

an increase of about 25.5%, close to the 26% measured. That is why NISR's annual rate (2.3%) is a little less than 2.6%.

Important

Case study: why Rwanda's growth has changed

1978–1991 (3.1% a year): many births and falling death rates meant very fast growth.
1991–2002 (1.2% a year): the slowest period. NISR explains that life expectancy fell from 54 to 51 years, because of the 1994 Genocide against the Tutsi, in which more than one million people were killed, and its effects: poverty and the disruption of health care and daily life.
2002–2022 (2.6%, then 2.3% a year): health centres spread across the country, vaccination reached about 96% of children, and safe water and housing improved. Death rates and infant mortality fell sharply, and life expectancy rose to 69.6 years. At the same time, fertility has been falling, so growth has begun to slow.

Warning

Per 1,000, not per cent. Birth and death rates are given per 1,000 people. A birth rate of 27.4 means 27.4 births per 1,000 people, which is 2.74%, not 27.4%. Divide by 10 to change "per 1,000" into "per cent".

The Rate of Natural Increase and Population Dynamics, by Heimler's History (7 min). Watch how the rate of natural increase is worked out from birth and death rates, then check it with Rwanda's figures in the table.

Discuss

The total fertility rate is 3.0 in the City of Kigali and 4.0 in the Eastern Province. Suggest three reasons why women in the city have fewer children on average, and say how this links to where people live and work.

Tip

Rule of 70. To estimate how long a population takes to double, divide 70 by its growth rate in per cent: at 2.3% a year, about $\frac{70}{2.3} \approx 30$ years.

✦

Practice

Define birth rate, death rate and natural increase.
A district of 400,000 people had 11,200 births in a year. Calculate its birth rate.
A country's birth rate is 32 per 1,000 and its death rate is 9 per 1,000. Find its natural increase as a percentage.
Rwanda's death rate fell from 17.1 to 6.3 per 1,000 between 1978 and 2022. By what percentage did it fall?
Using Figure 1, name the period of slowest growth and explain it.
Give three reasons why Rwanda's death rate has fallen.
Estimate how many years Rwanda's population would take to double at 2.3% a year.

Show answersHide answers

Birth rate: live births per 1,000 people in a year; death rate: deaths per 1,000 people in a year; natural increase: birth rate minus death rate.
$\frac{11\,200}{400\,000} \times 1\,000 = 28$ per 1,000.
$32 - 9 = 23$ per 1,000, which is 2.3%.
$\frac{17.1 - 6.3}{17.1} \times 100 \approx 63\%$ .
1991–2002 (1.2% a year): the 1994 Genocide against the Tutsi killed more than one million people, and poverty and the disruption of health care followed.
Any three: more health centres across the country; vaccination of almost all children; safer water; better housing and living conditions; better care for mothers and babies.
$\frac{70}{2.3} \approx 30$ years.

Remember

Population changes through births, deaths and migration; natural increase = birth rate − death rate.
Rwanda 2022: birth rate 27.4, death rate 6.3 per 1,000; TFR 3.6; life expectancy 69.6; growth 2.3% a year.
Rates per 1,000 ÷ 10 = per cent; growth compounds, like interest.

Sources and credits

NISR, Fifth Rwanda Population and Housing Census 2022, Main Indicators Report: Table 4 (census totals and growth rates), Tables 33 and 34 (births and fertility), Figures 12–14 and pages 44–45 (death rates, infant mortality, life expectancy).
Video: The RATE of NATURAL INCREASE and Population Dynamics, Heimler's History, embedded from YouTube.

Written by Ganzaa: the lesson text, chart, table, worked examples and practice.

1From 4.8 million to 13.2 million

2What makes a population grow or shrink

3Rwanda's population indicators

4Discuss

From 4.8 million to 13.2 million

What makes a population grow or shrink

Rwanda's population indicators

Discuss